Tecumseh Carburetor Manual

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TECUMSEH

POWER

Service Dealer’s and Technician’s Training and Informational Series

Carburetor Identification,

Troubleshooting and Service

TecumsehPower

ENGINES

& TRANSMISSIONS

Table of Contents

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

Engine Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

Fuel Recommendations. . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Storage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

High Altitude Jet for Emissionized Carburetors . . . . . . . . . . . . . . . . 3

High Altitude Carburetor Kits for Fixed Main Carburetors. . . . . . . . . . . 4

Throttle Control Brackets, Governors, and RPM Adjustments . . . . . . . . 5

How to Identify a Tecumseh Carburetor . . . . . . . . . . . . . 5 - 10

Non-TecumsehPower Carburetors . . . . . . . . . . . . . . . . . . . . . 10

Diaphragm Carburetors . . . . . . . . . . . . . . . . . . . . . . . . . 10 - 11

Carburetor Cleaning Series 8 - 11 . . . . . . . . . . . . . . . . . . . 12 - 16

Emission Carburetors . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

Pre-Sets and Adjustments (Non-Emission) . . . . . . . . . . . . . . . 18 - 20

Troubleshooting Carburetion Chart . . . . . . . . . . . . . . . . . . . 21 - 22

Troubleshooting TecumsehPower Carburetors. . . . . . . . . . . . . . . .. 2. 3

Troubleshooting Carburetion TC Series Chart . . . . . . . . . . . . . 24 - 25

Troubleshooting Walbro and Tillotson . . . . . . . . . . . . . . . . . . . . 26

Metering System. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

Service Carburetor Information . . . . . . . . . . . . . . . . . . . . . 27 - 28

Using the Computer Parts Look Up System. . . . . . . . . . . . . . . . . 29

Float Adjustment Procedure . . . . . . . . . . . . . . . . . . . . . . . . . 29

Carburetor Service Tips. . . . . . . . . . . . . . . . . . . . . . . . . 30 - 33

Primer Bulb Service . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

Fuel Filters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35

Internal Atmospheric Vent Passage . . . . . . . . . . . . . . . . . . . . . 35

Failure Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36 - 38

INTRODUCTION

This troubleshooting book is designed as a quick reference for carburetion problems and an aid in identifying failures

and their possible causes. It also directs the user to other publications and printed material that assist in properly

resolving problems or making adjustments not related to carburetion but could affect carburetion.

Listed below are some basic DO’S and DON’TS to be followed when making carburetor repairs.

PLEASE DO:

Follow all instructions carefully.

Use new service replacement screws (650506 Torx 8) for the choke and throttle shutters (screws are treated

with a dry-type adhesive to secure them in place).

Use Tecumseh float tool 670377 or an 11/64 drill bit to set the proper float height. Remove the bowl

gasket and measure from the casting surface. The gasket should be replaced and class="stl_43 stl_15">Use only genuine Tecumseh parts.

Remove all welch plugs, o-rings and non-metallic main nozzles before cleaning carburetor in cleaner.

DO NOT:

Use drill bits to clean passages.

Enlarge passages.

Soak carburetor in a cleaner over 30 minutes.

Reuse original choke and throttle shutter screws.

Interchange bowl nuts.

Reuse gaskets and “O” rings.

ENGINE TROUBLESHOOTING

When troubleshooting a carburetor, other areas such as valves, fuel tank venting or gaskets should not be

overlooked. The carburetor is dependent on the proper operation of the engine to do its job. The first step in

troubleshooting is to determine if you have a carburetor or an engineproblem.

In order for the engine to operate properly, the following items need to be checked first:

1. Makes ure there is a sufficient amount of clean, fresh fuel in the tank.

2. Check spark plug for proper reach, gap and condition. Replace, if needed, or in question. Perform an

ignition test using spark tester part number 670366 to assure that you havea crisp spark.

NOTE

On older point ignitions models check for proper ignition timing according to the Technician's handbook.

. Check for fuel flow restrictions into the carburetor. Deteriorated fuel line, and fuel cap venting are some of

the more common restrictions. TecumsehPower uses a stainless steel 75 micron filter screen molded

into most tanks. It is extremely rare for this area to become restricted and should be checked last.

. Check compression by first disconnecting the spark plug lead and ground it to prevent start-up. Next, turn

the engine over by hand. A definite resistance should be noticed on the compression stroke. Using a

cylinder leak down testeris also possible.

After these basic checks have been performed and you are satisfied with the engine's condition, attempt to start it. If it

does not start, remove the spark plug and check its condition. If it is dry, you can assume there is a problem with the

carburetor or the fuel system. Continue by troubleshooting the carburetor.

FUEL RECOMMENDATIONS

FUEL

TecumsehPower strongly recommends the use of fresh clean unleaded regular gasoline in all engines. Unleaded

gasoline burns cleaner, extends engine life and promotes better starting by reducing build-up of combustion chamber

deposits. Reformulated fuels containing no more than 10% Ethanol, 15% MTBE, 15% ETBE or premium gasoline can

be used if unleaded regular gasoline is not available. Leaded fuel may be used in countries where unleaded fuel is not

available. NEVER USE FUEL CONTAINING METHANOL.

Tecumseh Engine Storage

IF THE ENGINE IS TO BE UNUSED FOR 30 DAYS OR MORE

Gasoline (Fuel) vapors are highly flammable and can explode. Fuel vapors can spread and be

WARNING

ignited by a spark or flame many feet away from the engine. To prevent injury or death from fuel

fires, follow these instructions:

Never store the engine with fuel in the fuel tank inside a building with potential sources of ignition such as hot water

and space heaters, clothes dryer, electric motors, etc.

•

Gasoline can become unstable in less than 30 days and form deposits that can impede proper fuel flow and engine

operation. To prevent deposits from forming, all gasoline must be removed from the fuel tank and the carburetor.An

acceptable alternative to removing all gasoline is adding a fuel stabilizer such as Tecumseh Ultra-Fresh part

number 730245 to the gasoline. Fuel stabilizer should be added to the fuel tank or storage container. Always follow the

mix ratio found on the stabilizer container. Run the engine at least 10 minutes after adding the stabilizer to allow it to

reach the carburetor.

Draining the Fuel System

Do not attempt to pour fuel from engine or siphon fuel by mouth. Empty fuel tank by using a

WARNING

commercially available suction device designed for use with gasoline. Then run the engine until

any remaining fuel is consumed. Doing so may result in death or serious injury.

Drain the fuel into an approved container outdoors, and away from any open flame or combustion

CAUTION

source. Be sure the engine is cool.

NOTE

If gasohol has been used, put a small amount of unleaded gasoline into fuel tank and repeat preceding instructions,

then run engine until fuel is used up.

Oil Cylinder Bore

. Remove the spark plug wire from the spark plug. NOTE: Always ground the plug wire when disconnected.

Pull the starter handle slowly until resistance is felt from compression pressure, then stop. Slowly release

starter tension to prevent the engine from reversing due to compression pressure.

. Remove the spark plug, squirt 1/2ounce (15ml.) of clean engine oil into the spark plug hole.

. Cover the spark plug hole with a shop towel and crank the engine over slowly, several times.

. Replace the spark plug and tighten. Pull the starter handle as performed in step #1. The piston position

blocks the cylinder ports on 2 cycle engines or closes the valves on 4 cycle engines, preventing air from

entering and oil from leaving the cylinderbore during storage.

5. Re-connect the spark plug wire on the spark plug.

HIGH ALTITUDE JET

FOR EMISSIONIZED CARBURETORS

The following list of altitude compensation jets is being provided for use with emission grade carburetors at

elevations between 6,000 and 11,000 feet (1,824-3,344 meters).

This list applies only to engines which are identified as compliant with CARB (California Air Resource Board) or EPA

US Environmental Protection Agency) regulations.

To determine the proper jet for your carburetor, simply locate the number stamped into the original bowl nut. Then

use the chart below to identify and install the proper jet.

NOTE: Installation of altitude compensation jets is NOT WARRANTY

STANDARD JET

NUMBER

SERVICE

NUMBER

HIGH ALT. JET

BETWEEN 6,000 TO 11,000 FT

SERVICE

NUMBER

USE

(1,824 TO 3,455 M)

148

152

157

158

162

166

176

181

183

184

188

190

191

202

205

206

207

640181

640011

640032

640008

640024

640015

640059

640106

640114

640128

640170

640163

640162

640184

640208

640209

640210

203

640206

640114

640087

640062

640185

640008

640089

640188

640128

640209

640187

640011

640008

640186

640206

640181

640209

183

169

175

149

158

170

167

184

206

163

152

158

205

203

148

206

HIGH ALTITUDE CARBURETOR KITS

FOR FIXED MAIN JET CARBURETORS

NOTE

This list applies only to products built prior to emissions regulation. Engines which are identified as compliant with

CARB (California Air Resources Board) or EPA (US Environmental Protection Agency) regulations can NOT be

changed from their factory setting unless specifically authorized.

Engines built to O.E.M. specifications may experience starting and operating problems when used in areas where the

altitude is 4,000 feet (1220 meters) above sea level or higher.A leaner fuel/air mixture is desirable at higher elevations

to sustain good engine startability and operating characteristics. Engines built with adjustable idle and main circuit

carburetors can be adjusted to optimize performance.

The following will assist you in selecting the correct high altitude/leaner jetted bowl nut for engines equipped with fixed

main or dual system carburetors. Order parts from your Authorized Tecumseh Engine Distributor or Dealer.

CYCLE

STANDARD BOWL/NUT

STAMPED

ENGINE

Over 4,000 Ft.

TVS90-120/ECV90,100/TNT100

64, 65, 75, 79, 103,-

08, 126, 127, 137

632455

632737

631026

632239

633017

632648

632638

632239

631973

632688

TVS90-120 / OHH50 / 55

TVS90 -120, OVRM40-60

OVM & OVXL120, OHV11-13 (Formula)

Dellorto

158, 161, 164, 165, 166, 171, 172, 177

124, 125,133, 135, 136

120, 141

VLV40, 50, 55, 60

Jet

VLV40, 50, 55, 60

Nozzle

83, 132

109, 131

Jet

TVM170-195

TVM220

OHV15 - Walbro LMK26

CYCLE

AH/AV520 & 600, HSK600

101

L118, L119

124, 125

Jet

632368

632463

631026

632940

N/A

TVS/TVXL840

HSK840, 845, 850/HXL840

TC200/TC300 Tillotson carburetor only.

TC200/TC300 Tillotson HU112 and HU114

Jet

Do not install leaner jetted bowl nuts on engines used below four thousand feet as starting and operating problems will

occur. DOING SO WILL VOID THE ENGINE WARRANTY.

THROTTLE CONTROL BRACKETS,

GOVERNORS AND RPM ADJUSTMENTS

Before adjusting any mixture screws, reset the screws to the recommended carburetor presets. Check for proper

governor adjustments as outlined in the appropriate Technician's Handbook. Identify the locations of your high speed

and low speed RPM adjustment screws. Check to make sure that the throttle control brackets are adjusted properly to

allow for full choke. Always make sure that normal maintenance procedures (ie., oil, fuel, air cleaner, etc.) have been

checked. Consult microfiche card #30, the computer parts look up system or Service Bulletin #107 for C.P.S.C.

specifications to determine the proper RPM settings. Start the engine, allow it to warm up, the carburetor can then be

adjusted for optimum performance by using the information outlined in this book. Now the low and high speed screws

can be adjusted to the recommended RPM's.

How To Identify a Tecumseh Carburetor

TecumsehPower has a variety of carburetors. To help identify these carburetors here are some simple procedures to

follow.

DUAL SYSTEM CARBURETORS

The easiest way to identify the dual system carburetor is

by the presence of a large primer bulb located on the

side of the carburetor. The absence of adjustment

needles help to identify the carb as well. The dual

system carburetor is used on 4-cycle vertical crankshaft

rotary mower engines.

SERIES 1 CARBURETORS

Series 1 carburetors come in a variety of styles. They

are used on both 2 and 4-cycle vertical and horizontal

shaft engines in the 2 through 7 h.p. range. It is a float

style carburetor with a smaller venturi than the Series 3

and 4 carburetors. Some will have an adjustable idle

and main and others will have a fixed main with an

adjustable idle. There are also some fixed speed

applications that will only have a fixed main system and

the idle system will not be drilled.

SERIES 1 EMISSION

This carburetor is similar to the standard Series 1

carburetor. The emission equivalent has a fixed idle and

main. The idle restrictor jet will be capped to prevent

access unless the cap is removed. The fixed main jet is

part of the bowl nut. Aball plug is visible from the bottom,

which seals the passage. This carburetor also has a

serviceable main nozzle emulsion tube.

How To Identify a Tecumseh Carburetor

(CONTINUED)

SERIES 2 CARBURETORS

Series 2 carburetors were used on outboard engines.

This carburetor is the same as the Series 1 with the

exception of the remote adjustable idle mixture screw,

and a built infuel pump.

Series 2 carburetors have a built-in fuel pump consisting

of a fuel pump element which inflates and deflates with

crankcase pulsations which opens and closes two flap

valves in the fuel pump, there by pumping fuel from a

remote tank to the carburetor float bowl.

When replacing the fuel pump element, install with the

slot opening at a 45 angle as illustrated. Installation in

any other position will damage the diaphragm.

SERIES 3 & SERIES 4 CARBURETORS

Series 3 and 4 carburetors are generally used on 8

through 12.5 horsepower 4-cycle engines. The venturi

size of these carburetors are larger than Series 1 and

Dual System Carburetors. The quickest way to identify

these carburetors is by the presence of bosses on each

side of the idle mixture screw.

SERIES 3 and SERIES 4 EMISSION

This carburetor is similar to the standard Series 3 and 4

carburetor with a few subtle differences. The emission

equivalent has a fixed idle and main. The idle restrictor

jet will be capped to prevent access unless the cap is

removed. The fixed main jet is part of the bowl nut. A ball

plug is visible from the bottom, which seals the passage.

This carburetor also has a serviceable main nozzle

emulsion tube.

FIXED IDLE

FIXED MAIN

How To Identify a Tecumseh Carburetor

(CONTINUED)

To determine whether the carburetor is a Series 3 or

Series 4, look at the throttle or choke end of the

carburetor.

Series 3 will have one screw on the throttle and choke

plates.

The Series 4 will have two screws on the throttle and

choke plates.

SERIES 3

SERIES 4

VECTOR CARBURETORS

The Vector carburetor is a float feed, nonadjustable

carburetor, with a one piece extruded aluminum body.

The float bowl, float, nozzle, and venturi are nonmetallic,

which eliminates the corrosion and varnishing problems

associated with similar metallic parts. Common service

areas of the carburetor are contained in the fuel bowl,

which include the float, needle, seat and main nozzle

emulsion tube. All of these parts can be serviced without

removing the carburetor body from the engine.

NOTE

If the unit was run with poor filter maintenance the

venturi should be removed and the air bleeds cleaned

with solvent.

SERIES 6 CARBURETORS-4 CYCLE

Series 6 carburetors are used on 2 and 4-cycle engines.

They have a larger venturi than the dual system

carburetor and use a simple fixed idle system. Series 6

carburetors used on both vertical and horizontal

applications are nonadjustable. The 4-cycle version

pictured has a stepped primer bulb.

How To Identify a Tecumseh Carburetor

(

CONTINUED)

SERIES 6 CARBURETORS - 2-CYCLE

Series 6 carburetors used on TVS/TVXL840 engines

are similar in appearance and operation to the

carburetors used on 4-cycle engines with the following

differences:

. The bowl nut is left-hand thread. This bowl nut

is identified by an "L" stamped on the nut and

the international left thread notches across the

points.

2. A dampening spring is installed on the float

hinge pin to reduce erratic float travel.

3. The two mounting bosses extend out from the

carburetor body.

CUTLINE

SERIES 7 CARBURETORS (EMISSION)

The Series 7 carburetor is an emissions grade

carburetor used on medium frame vertical shaft

overhead valve engines. It has a non-metallic bowl and

a snap-on bowl retainer to connect it to the carburetor

body. This model has a fixed main jet and a fixed idle jet;

both are located in the carburetor bowl. The float bowl,

float, nozzle, and venturi are non-metallic, which

eliminates the corrosion and varnishing problems

associated with similar metallic parts. Common service

areas of the carburetor are contained in the fuel bowl,

which include the float, needle, seat and main nozzle

emulsion tube. All of these parts can be serviced without

removing the carburetor body from the engine.

SERIES 8 CARBURETOR (EMISSION)

The Series 8 carburetor has both a fixed main and idle

circuit. The fixed idle system is achieved by a restrictor

jet that meters the fuel for the idle circuit. The idle

restrictor jet will be capped to prevent access unless the

cap is removed. The fixed main jet is part of the bowl

nut. A ball plug is visible from the bottom, which seals

the passage. This carburetor also has a serviceable

main nozzle emulsion tube. It also has a stepped primer

bulb.

How To Identify a Tecumseh Carburetor

(CONTINUED)

SERIES 9 CARBURETOR

The Series 9 carburetor is an emissions carburetor that

uses the same carburetor body as the Series 8 but with a

simple fixed idle system, identical to the one used on the

Series 6 carburetor. It has the idle discharge port located

at the 7 o'clock position on the throttle end of the

carburetor. Identify this carburetor by the stepped primer

bulb, the presence of a non-drilled idle mixing well and a

serviceable main nozzle emulsion tube.

SERIES 10 (EMISSION)

The Series 10 carburetor is identical to the Series 8

carburetor with the addition of a choke. To assist in cold

weather starts. It has a fixed idle and main. The idle

restrictor jet will be capped to prevent access unless the

cap is removed. The fixed main jet is part of the bowl nut.

A ball plug is visible from the bottom, which seals the

passage. This carburetor also has a serviceable main

nozzle emulsion tube. It also has a stepped primer bulb

to assist in starting.

SERIES 11

This carburetor adds a fuel chamber, built into the

carburetor body, that feeds fuel into the venturi during

the initial warm up period. This patented feature

eliminates, hunting, surging and false starts inherent to

emissions engines. However external identification of

the Series “11” carburetor has been a challenge. To

make this ID simple, the Series “11” carburetor idle

restrictor cap will be black, and all others will be gray. The

part number for the black cap is 640200 and the gray is

640053.

SERIES 11 BRIDGED

CAPPED JET

This carburetor is identical to the Series “11” with the

exception of the center leg. Anon-metallic jet is pressed

into the center leg to allow additional fuel into the main jet

for applications that require this fuel to enhance run

performance

NONMETALLIC JET

CARBURETOR CLEANING - SERIES 11 and SERIES

11 BRIDGED

With the additional fuel well welch plug removed, you

can see the small plastic metering jet, which can be

distorted if left to soak in a carb dip tank. Currently, this

metering jet is not a serviceable part. Our position has

been to soak a carburetor no more than ½ hour but the

exception is the Series 11 carburetor. To be safe, service

all TecumsehPower carburetors with Carburetor Spray

BRIDGED

SERIES 11

STANDARD 11

696410 along with a .012” (.304mm) gauge wire.

NON-Tecumseh CARBURETORS

DELLORTO CARBURETOR

The Dellorto carburetor is similar to the dual system

carburetor. It has no adjustments and has a primer assist

start. It has a noncorrosive float and the needle is viton

tipped, eliminating the viton seat found in the dual system

carburetor. The angle of the fuel inlet is adjustable and

attached to the carburetor body with a banjo bolt. This

carburetor is used on some TVS rotary lawnmower

engines.

WALBRO LMK CARBURETOR

The Walbro LMK has a large venturi and a fixed main with

an adjustable idle. It is used on some OHV engines. This

carburetor has a noncorrosive float and a viton tipped

needle. It also has a nonmetallic choke shaft. It is easily

identified by the Walbro name on the carburetor body

next to the idle adjustment screw.

WALBRO WHG CARBURETOR

The WHG, used on OH cast iron engines, can be built as a

fully adjustable, single adjust or nonadjustable

carburetor. It has a large venturi. Its most recognizable

feature is the large square mounting surface on the choke

end of the carburetor.

DIAPHRAGM CARBURETORS

TECUMSEH DIAPHRAGM CARBURETORS

The diaphragm carburetors are unique. These

carburetors can be operated at a more severe angle

than float style carburetors. They still require that the

fuel supply be located in a position that allows it to be

gravity fed. Its most distinctive feature is the lack of a

fuel bowl.

DIAPHRAGM CARBURETORS

(CONTINUED)

WTA WALBRO CARBURETOR

The WTA carburetor has a rubber-type diaphragm,

which is exposed to intake pressure on one side and to

atmospheric pressure on the other. The WTA is used on

TC200 and 300 engines. There are two adjustment

screws. They are the idle mixture screw and the idle

RPM screw. The WTA has a choke and an all metal fuel

inlet fitting. The Walbro name is molded onto the pump

cover.

WT WALBRO CARBURETOR

The WT Walbro carburetor is used on the TC-II style

engine. It is similar to the WTA carburetor but its reverse

image. The WT has no choke lever and has a

combination plastic and metal fuel inlet fitting.

TILLOTSON HU CARBURETOR

The Tillotson HU carburetor is the reverse image of the

WTA Walbro carburetor. It is used on the TC-II. The

Tillotson HU has a replaceable main and Tillotson is

visible on the pump cover.

Tecumseh TC CARBURETOR

This carburetor has a fixed idle and main which meets

the emissions standards for two cycle engines.

The main jet is serviceable and can be accessed by removing the

plastic cap. The jet is removed for cleaning purposes

only, and must be covered after servicing to maintain

compliance with emissions regulations.

Tecumseh Carburetor Cleaning SERIES 8-11

. Remove bowl and push the float hinge pin out with

carb tool part # 670377. The float cannot be rotated

upward.

. Remove the seat with the carb tool.

. Remove the emulsion tube by gently inserting the

carb tool. Rotate the hook end until you locate the air

bleed passage. Then with hook in place, pull the tube

out.

. Remember there are two "O" rings on the emulsion

tube. You may have to go into the center leg a second

time to remove the upper second"O"ring.

Cleaning a Tecumseh Carburetor SERIES 8-11

(CONTINUED)

SMALL CHISEL

PIERCE PLUG WITH TIP

PRY OUT PLUG

WELCH PLUG TO BE

REMOVED

. Remove the extended prime well welch plug with a

sharpened chisel. When piercing through the

extended prime well welch plug, pound close to the

red primer bulb side as not to mar the casting.

DO NOT ALLOW

CHISEL POINTTO

STRIKE

ABOUT 1/8” WIDE

CARBURETOR

BODY OR CHANNEL

REDUCER

SMALL CHISEL

6. Clean the extended prime well w/.012" tag wire and

carb spray.

. Remove the idle prime well welch plug. Using a

sharpened chisel or punch. Clean the progression

holes and the idle air bleed hole using tag wire and

carb spray. If damage occurs in progression holes,

replace with a new carburetor.

8. Remove the idle restrictor cap and clean the idle jet

with tag wire andcarb spray.

How To Clean a Tecumseh Carburetor SERIES 8 - 11

(

CONTINUED)

Clean the idle circuit fuel pick-up located in the

center leg using tag wire.

0. The Series 11 bridged carburetor has an

additional idle circuit fuel pick-up jet on the side of

the center leg. Clean this with .012" (.3 mm) tag

wire.

1. Clean main jet (bowl nut) with tag wire. Remember

there are three drilled passages.The fuel pick-up,

the main jet and the idle delivery hole.

12. Spray all cavities with Tecumseh carburetor

spray part #696410.

How to Clean a Tecumseh Carburetor SERIES 8-11

(CONTINUED)

WELCH

PLUGS

3. Replace the welch plugs included in carb kit with a

flat punch and apply fingernail polish to the edge

where the plug meets the casting.

14. Note that a seat has a grooved end (shown) is

installed first into the carburetor casting.

15. Install seat into the orifice with the carb tool until it

bottoms on the casting.

6. Check the float height with the carb tool. When the

carb tool is removed, the float should remain in

position. The dimension of the carb tool flats are

11/64".

Cleaning a Tecumseh CarburetorGSERIES8-11

(

CONTINUED)

7. Adjust the float if necessary by bending the metal tang.

8. Bring the float/needle assembly down into position,

then insert the float hinge pin.

Always remember the open end of the needle

clip on a Tecumseh carburetor, faces out

toward the air cleaner side.

9. Install a new float bowl, bowl "O" ring, and the bowl

nut with a new bowl nut gasket.

EMISSION CARBURETORS

The following information will help you better identify

some of the common components of emission grade

carburetors. Emission carburetors will be internally

vented. On the Series 7, 8, 9, 10, 11 and 11 Bridged the

atmospheric vent hole is increased in size from earlier

model carburetors. This passage way leads to the

atmospheric vent chamber which is double vented into

the bowl cavity. This double venting is common on

emissions grade carburetors.

IDLE MIXING

WELL

ATMOSPHERIC

VENT PASSAGES

MAIN NOZZLE

AIR BLEED

IDLE FUEL

TRANSFER

PASSAGE

NOTE

Emissions certified parts can be identified by a specific

series of numbers. Emissions carburetors and

carburetor parts will be identified using a 640,000 and

higher series number. Engine parts that are emissions

certified will carry a 40,000 and higher series number.

The fuel metering jets are fixed on both the idle and high

speed circuit. The bowl nut on the Series 1, 3, 4, 8, 9, 10

and 11 and 11 Bridged are drilled from the bottom and

plugged for the main. The Vector and the Series 7

carburetors use a non-metallic jet held in place by the

bowl drain screw to meter fuel for the main.

“

O” RING

SPRING

MAIN JET

DRILLED BOWL NUT

NOTE

The Series 9 carburetor becomes emission compliant

when used on a fixed speed rotary mower application.

The idle on the Series 8 is metered using a threaded

restrictor (See illustration). Proper torque of this screw is

critical and should be torqued to 5-8 in. lbs. or .5 to 1 nm.

If it is not, it may vibrate loose. When the restrictor is

placed in the idle circuit passage it is capped with a

tamper resistant plastic cap. Tampering is considered

the rejetting or modification through resizing of the

jet. If the jet is removed for cleaning it must be recapped

to prevent tampering when it is re-installed. On the

Vector and Series 7, a small brass jet in the center leg

idle passage in the bowl is used to meter fuel for the idle.

IDLE RESTRICTOR

CAP

The throttle shutter will have a coined edge or a fine

blank edge for improved sealing capabilities. The scribe

mark must always face out. The position of the mark is

determined by engine size (page 31).

COINED EDGE

FINE BLANK EDGE

Emissions carburetors will have a serviceable plastic

main nozzle emulsion tube. This tube is sealed on both

ends using "O" rings or a gasket. These components are

critical to the emission grade engine in obtaining

repeatable emissions certification. The gasket used on

the Series 7 and Vector carburetors acts as a seal and is

used instead of an "O" ring.

NOT USED ON SERIES 7

or VECTOR CARBS.

“

O” RING ON

TOP OF STEP

IN GROOVE)

(

“

O” RING IN GROOVE

“

O” RING

How To Adjust a Tecumseh Carburetor

(NON-EMISSION)

Tecumseh Power CARBURETORS

Pre-sets and Adjustments

SERIES 1

Engine Model

Main Pre-set IdlePre-set

All models with float-type

carburetors

1-1/2 turn

1 turn

All models with diaphragm-type

carburetors

1 turn

MAIN AND IDLE PRE-SETS

IDLE MIXTURE

SCREW

MAIN MIXTURE

Turn both main and idle mixture adjusting screws in

(clockwise) finger tight. (CAUTION: Over-tightening will

SCREW

damage the taper portion of the needle.) Then back the

screws out (counterclockwise) to the pre-set figure in the

chartshownabove.

SERIES III, IV

NOTE

Some carburetors have fixed main jets. The absence of

the adjusting screw indicates a fixed jet and no

adjustment is necessary.

IDLE MIXTURE

SCREW

MAIN MIXTURE

SCREW

DIAPHRAGM

“

F”

DESIGNATION

FUEL ADJUST

AIR ADJUST

IDLE MIXTURE

SCREW

NOTE

Series 1 carburetors are built with one of two different

styles of adjustment needle for the idle. The long needle

is used on air adjust systems. The short needle on fuel

adjust systems. The adjustments are the same for both

systems, however, the drop off point may not be as

noticeable.

MAIN MIXTURE SCREW

Never operate the engine with

CAUTION

covers or guards removed. Rotating

parts can cause severe injury. Keep hands, feet, hair,

jewelry and clothing away from all moving parts.

FINAL ADJUSTMENTS (MAIN)

Engage the driven equipment (cutter deck, impeller, etc.)

so as to put the engine under a load condition.

Start the engine and allow it to warm up to normal

operating temperature (3-5 minutes). Set the speed

control to HIGH or FAST position, then turn the main

mixture adjustment screw in (clockwise) slowly until the

engine begins to run erratic. Note the position of the

screw. Now, turn the screw out (counterclockwise) until

the engine begins to run erratic. Turn the screw in

If the engine stops or hesitates while engaging the load

(

lean), turn the main mixture adjusting screw out

counterclockwise) 1/8 turn at a time, testing each

setting with the equipment under load, until this condition

is corrected.

(

(clockwise) midway between these two positions. This

If the engine smokes excessively (rich), turn the main

adjusting screw in (clockwise), 1/8 turn at a time, testing

each setting with the equipment under load, until this

condition is corrected.

will be the best setting.

Set the speed control to the IDLE or SLOW position

check for proper IDLE or LOW speed RPM and adjust

the idle mixture screw in the same manner as the main

mixturescrew.

After the main mixture is set, move the speed control to

the IDLE or SLOW position. If the engine does not idle

smoothly, turn the idle mixture screw 1/8 turn either in

If further adjustment is required, the main adjustment

should be made with the engine under a loaded

condition.

(

clockwise) or out (counter clockwise) until engine idles

smoothly.

Recheck your HIGH and LOW RPM settings and adjust

as necessary.

How To Adjust a Tecumseh Carburetor

(CONTINUED)

RPM ADJUSTMENTS

Now, the LOW and HIGH speed screws can be adjusted to the recommended RPM's. First identify the location of both

HIGH and LOW speed RPM adjustment screws, then identify the recommended HIGH and LOW RPM settings

according to microfiche card 30, the computer parts look-upsystem or Service Bulletin #107 for rotary mowers.

GOVERNED / NON-GOVERNED IDLE

With the engine running at the lowest speed set the governed idle at the designated RPM by bending the idle RPM tab.

Next set the non-governed idle by pushing the bottom of the governor lever away from the control brackets, so the

throttle lever contacts the idle speed screw. Hold the lever in this position and turn the idle adjustment screw clockwise

to increase or counter clockwise to decrease engine idle speed. The setting on the carburetor screw should be set 600

RPM below the tab or governed idle setting.

WALBRO CARBURETORS 4CYCLE

PRE-SETS AND ADJUSTMENTS

Carburetor Model No.

LMH

Main Pre-set

1-1/2turn

1-1/4turn

1turn

IdlePre-set

1-1/2turn

1-1/4turn

WHG&LME

LMK

FIXED

MAIN AND IDLE PRE-SETS

Turn both the main and idle mixture adjusting screws in

clockwise) finger tight. (CAUTION: Over -tightening will

IDLE MIXTURE

SCREW

MAIN MIXTURE

SCREW

(

damage the tapered portion of the needle.) Now back

the screws out (counterclockwise) to the pre-set figure

in the chart shown above.

CARBURETOR

MODEL

NUMBER

NOTE

Some carburetors have fixed main jets. The absence of

the adjusting screw indicates a fixed jet and no

adjustment is necessary.

FINAL ADJUSTMENTS

IDLE MIXTURE

SCREW

Start the engine and allow it to warm up to normal

operating temperature (3-5 minutes). Set the speed

control to HIGH or FAST position, then turn the main

mixture adjustment screw in (clockwise) slowly until the

engine begins to run erratic (lean). Note the position of

the screw. Now turn the screw out (counterclockwise)

until the engine begins to run erratic (rich). Turn the

screw in (clockwise) midway between these two

positions. This will be thebest setting.

FIXED MAIN

Set the speed control to IDLE or SLOW position and

adjust idle mixture screw in the same manner as the

mainmixturescrew.

MAIN MIXTURE

SCREW

IDLE MIXTURE

SCREW

If the engine stops or hesitates while engaging the load

lean), turn the main mixture adjusting screw out

counter clockwise) 1/8 turn at a time, testing each setting

with the equipment under load until this condition is

corrected.

Now the LOW and HIGH speed governor adjustment

screws can be set to the recommended RPM's. First

identify the location of both HIGH and LOW speed

governor adjustment screws, then identify the

recommended HIGH and LOW RPM settings according

to microfiche card 30.

(

If the engine smokes excessively (rich), turn the main

adjusting screws in (clockwise) 1/8 turn at a time, testing

each setting with the equipment under load, until this

condition is corrected.

If further adjustment is required, the main adjustment

should be made under a load condition.

After the main mixture is set, move speed control to the

IDLE or SLOW position. If the engine does not idle

smoothly, turn the idle mixture screw 1/8 turn either in

Never operate the engine with

CAUTION

covers or guards removed. Rotating

parts can cause severe injury. Keep hands, feet, hair,

jewelry and clothing away from all moving parts.

(

clockwise) or out (counterclockwise) until engine idles

smoothly.

Engage the driven equipment (cutter deck, impeller,

etc.) so as to put the engine under a loaded condition.

Recheck your HIGH and LOW RPM settings and adjust

as necessary.

How To Adjust a Tecumseh Carburetor

(CONTINUED)

WALBRO CARBURETORS 2-CYCLE

PRE-SETS AND ADJUSTMENTS

IDLE SPEED

ADJUST

IDLE MIXTURE

SCREW

Carburetor Model No. Main Pre-set

Idle Pre-set

1-1/4 turns

WTA&WT

FIXED

TILLOTSON CARBURETOR2-CYCLE

PRE-SETS AND ADJUSTMENTS

Carburetor Model No. Main Pre-set

Idle Pre-set

1-1/2 turns

FIXED

IDLE PRE-SET

Turn idle mixture adjustment screw (clockwise) finger

tight to closed position, then turn the screw

counterclockwise) according to the above chart. This

setting will allow engine to be started so carburetor can

be fine tuned.

TILLOTSON HU

CARBURETOR

(

FINAL ADJUSTMENT

Idle Mixture: Start the engine and let it reach its normal

operating temperature (3-5 minutes). Begin slowly

turning the idle mixture screw in (clockwise). As you turn

it in (clockwise), the engine will begin to falter, this is the

leandropoffpoint.

IDLE MIXTURE

SCREW

IDLE SPEED

ADJUST

NOTE

If the RPM is greater than 2,400 stop the procedure and

reduce idle RPM. Settings above 2,400 will cause fuel

from the main jet to contribute to the idle mixture creating

an inaccurate idle mixture setting. Turn the needle out

until the engine begins to falter. Note this position, this is

the rich drop-off. Your final needle setting is halfway

between the rich and the lean drop-off points. Once the

mixture is set, the idle speed needs to be adjusted. Set

the idle speed at the recommended RPM.

WALBRO WT

CARBURETOR

WALBRO CARBURETORS 4-CYCLEFIXED(WHG)

(

OH120-180)

On occasions high altitude has affected the operation of

high and low speed performance. To correct this

situation use the following steps:

. Remove air cleaner assembly.

. Remove choke shaft assembly.

. Using an ice pick type tool with a small hook on the

end, remove the brass cup plug out of the nozzle well

vent.

NOTE

Do not use a thread tap as chips may enter the

carburetor.

IDLE AIR RESTRICTOR

. Reassemble choke shaft assembly.

. Reinstall air cleanerassembly.

CARBURETOR TROUBLESHOOTING

Tecumseh CARBURETORS

FLOAT AND DIAPHRAGM

FUEL SYSTEM

Improper Priming Procedure

Bad Bowl Gasket

•

• •

Plugged Tank Filter or Vent

Fuel Pick-up Restricted

Idle Port Restricted

•

• •

•

• • •

• •

•

• • •

•

• •

Damaged Adjustment Needles

Incorrect Float Height

•

• • • • • • •

•

Main Nozzle Restricted

• •

• • • •

Dirty, Stuck, Needle and Seat

•

EMISSION

Fuel Inlet Plugged

•

“

O” Ring Mission or Damaged

Emulsion Tube

• • • •

• •

CARBURETOR TROUBLESHOOTING

Tecumseh Engine CARBURETORS

FLOAT AND DIAPHRAGM CARBURETORS

AIR SYSTEM

Plugged Air Filter

•

• •

Leaky Carburetor Gaskets

Throttle or Choke Shafts Worn

Choke not functioning properly

Plugged Atmospheric Vent

Air Bleed Restricted

•

• •

•

• • •

•

• • • • •

•

Damaged or Leaky “O” Ring

•

• •

DIAPHRAGM SYSTEM

Damaged Diaphragm

Stuck or Dirty Ball Check

Diaphragm Upside Down

• •

•

• • • • • •

• • •

•

Troubleshooting

Tecumseh Carburetors

SECONDARY IDLE

DISCHARGE

NOT OPERATING)

MIXING WELL

Use the troubleshooting chart to determine the cause of a

particular carburetor problem. Once the problem is

identified, it will be necessary to select the proper corrective

action.

IDLE

AIR BLEED

(

MAIN NOZZLE

AIR BLEED

IDLE MIXTURE

IDLE

ADJUSTMENT

SEAT

Most repairs will consist of one of the following items:

. At times it will be necessary to thoroughly clean the

carburetor. First remove all welch plugs, adjustment

screws, "O" rings and the needle and seat. After soaking

the carburetor in a commercial cleaner for no longer

than 30 minutes, use compressed air or a soft tag wire to

clean passages.

IDLE

ADJUSTMENT

SCREW

MAIN JET

. If parts are worn or damaged, determine the extent of the

damage. Check to see if the repair be made by just

replacing parts or if the body of the carburetor is worn

and in need of replacement.

IDLE PICK-UP

SERIES 7

MIXING WELL

ATMOSPHERIC

VENT PASSAGES

IDLE

. Always replace throttle and choke shutter screws with

new service screws (650506). New service screws have

a dry adhesive on the threads. Replace all gaskets.

AIR BLEED

IDLE

RESTRICTOR

MAIN NOZZLE

AIR BLEED

IDLE/TRANSFER

FUEL

PASSAGE

IDLE SPEED ADJUSTMENT

SCREW

CHOKE SHAFT AND LEVER

THROTTLE SHAFT

ANDLEVER

MAIN JET

SPRING

CHOKE SHUTTER

SERIES 8

ATMOSPHERIC

VENT

DETENT REFERENCE

MARK ON THROTTLE

SHUTTER

MIXING WELL

MAIN NOZZLE

IDLE

THROTTLE SHAFT

RETURN SPRING

AIR BLEED

*INLET

IDLE

METERING

JET

MAIN NOZZLE

AIR BLEED

THROTTLE

SHUTTER

FITTING

SCREEN

IDLE AND

*INLET

INTERMEDIATE

FITTING

IDLE/TRANSFER

FUEL

AIR BLEED

ORIFICE

INLET SEAT

GASKET

PASSAGE

IDLE MIXTURE

ADJUSTMENT

SCREW AND

O” RING

If Present)

*DIAPHRAGM

GAKSET

SERIES 9

“

INLET NEEDLE

(

SEATAND

SPRING

MAIN MIXTURE ADJUSTMENT

SCREW AND “O” RING

If Present)

ATMOSPHERIC

VENT

ASSEMBLY

(

IDLE/TRANSFER

FUEL

DIAPHRAGM

PASSAGE

ATMOSPHERIC

VENT HOLE

WELCH PLUG (If Present)

MAIN NOZZLE CHECK BALL (If Present)

MAIN NOZZLE

AIR BLEED

IDLE

AIR BLEED

*NON-METALLIC ITEMS - CAN BE DAMAGED BY HARSH

IDLE

CARBURETOR CLEANERS

FUEL PASSAGE

CARBURETOR TROUBLESHOOTING

TC SERIES

ADJUSTMENTS

Low

•

• •

• • •

• • • • •

High

FUEL SYSTEM

Plugged Tank Filter or Vent

Restricted Fuel Line

•

• • •

•

Dirt in Fuel Passage

• •

•

Loose, Damaged Fuel Line

Leak in Pulse System

• •

• • •

Restricted Pulse Channel

Loose Pump Cover Screw

Defective Pump Diaphragm

•

• • • • • •

•

AIR SYSTEM

Plugged Air Filter

•

• • • •

Defective Manifold Gasket

Loose Carb. Mounting Bolts

Worn Throttle Shaft or Valve

•

Incorrect Throttle Assembly

Loose Throttle Valve Screw

Throttle Shaft Too Tight

Bent Throttle Linkage

•

Defective Throttle Spring

Bent Throttle Stop Lever

Choke Not Functioning Properly

Worn Choke Shaft or Valve

•

CARBURETOR TROUBLESHOOTING

TC SERIES

(

CONTINUED)

METERING SYSTEM

LEVER

Worn Lever

•

Set Too High

Set Too Low

Not Free

• •

•

• • • • •

• •

SPRING

Distorted

•

Improperly Installed

DIAPHRAGM

Leaking (Air / Fuel)

•

• •

•

• •

Worn Button

Improper Assembly

Defective Gasket

Loose Diaphragm Rivet

Hole in Diaphragm

Loose Cover Screws

•

• •

•

• •

•

• •

• • •

INLET NEEDLE & SEAT

Foreign Matter

Binding

• •

• • •

• • • • •

• •

• • •

•

• •

Worn Needle Body or Tip

•

NOZZLE CHECK VALVE

• • •

TROUBLESHOOTING

WALBRO WTA, WT, AND TILLOTSON HU

DIAPHRAGM PUMP CARBURETORS

TC SERIES CARBURETOR

The Walbro and Tillotson diaphragm pump carburetors

operate similarly by using a diaphragm impulse fuel pump

and a diaphragm / needle metering system. The most

common problems associated with these carburetors will

be found in these two areas.

PUMP DIAPHRAGM

OUTLET CHECK VALVE INLET CHECK VALVE

PULSE

CHANNEL

Fuel Pump. The fuel pump is normally trouble-free, but

some problems that may arise are:

FUEL INLET

IDLE PARTS

The diaphragm check valve can become stuck in

place by fuel deposits such as gum and varnish. This

would stop the flow of fuel through the carburetor.

IDLE

MIXTURE

ADJUSTING

SCREW

MAIN NOZZLE

The ribs on the face of the cover can become

damaged through misuse and will allow the pump to

leak.

METERING

LEVER

The smooth machined surface where the check

valves seat can get scratched or nicked, again

causing the pump to leak.

INLET NEEDLE

METERING DIAPHRAGM

METERING SPRING

ATMOSPHERIC VENT

METERING SYSTEM

The metering system is made up of four main parts:

4. The metering spring can be damaged or the wrong

spring installed affecting the acceleration and

deceleration characteristics of the engine.

Metering Diaphragm

Metering Lever

Metering Spring

Metering Needle

5. The metering needle, or its seat, could be worn

causing fuel under pressure from the pump to

bypass and flood the engine.

Some of the problems that could occur in this system are:

To troubleshoot the complete carburetor system, refer to

The diaphragm is damaged or torn resulting in a the Carburetor Troubleshooting Charts in this book.

failure to allow fuel to flow from the pump to the

metering side of the carburetor.

The diaphragm gets hard or stiff from stale fuel,

slowing its response time and causing the engine to

starve for fuel at high speeds.

The metering lever can be improperly adjusted

causing a rich or lean running condition.

SERVICE CARBURETOR INFORMATION

To identify a carburetor for replacement on an engine, use

ALTERNATE LOCATION

FOR MANUFACTURING

NUMBER

the model and specification number of the engine. If the

engine model and specification number are not present for

some reason, there is a model and code date number

stamped on the body of every carburetor.

Manufacturing Number

Month Year

Work Day of Mo.

162

CARBURETOR

DATE CODE

MANUFACTURING

NUMBER

MFG. TO SERVICE NO.

With the model number, you will be able to find all of the

information needed to repair or replace the carburetor. In

the Master Parts Manual or the microfiche carburetor

section, locate the manufacturing to service number cross

reference list. Find the service part number listed for the

carburetor. It will also list the page or grid where the

carburetor breakdown can be found.

Mfg.

Service

Page

No.

Mfg.

Service

Model No. Part No.

Model No.

Part No.

154

155

156

631176

631195

631182

631181

631185

631217

631186

631213

631211

631210

631196

631244

631209

631241

631928

631215

631218

206

215

216

217

220

221

222

223

224

225

226

227

229

230

231

232

233

234

631375

631286

631301

631297

631299

631312

631290

631294

631298

631295

631311

631310

631341

631349

631316

631313

157

158

159

160

161

162

163

164

165

166

167

168

169

170

171

Std

Pkg Part

Code Description

Std

Pkg Part

Code Description

Qty Number

Supersedence Qty Number

Supersedence

631183

631184

631190

631191

WASHER

O RING

WASHER

631785A

631786

631787

631788

631788A

631789

631789A

631790

631790A

631791

631792

631792A

631793

631794

631794A

631795

631795A

SVC CARB NF

SERVICE CARB

When referencing the carburetor in the price list, the original

carburetor may be superseded to a service carburetor.

Some TecumsehPower service carburetors will not have

the fuel fitting. These carburetors can be identified by the

description listed as SVC Carb NF, meaning service

carburetor, no fitting. If this designation is not made in the

listing, the carburetor will have a fuel fitting.

USE 631788A

SVC CARB NF

USE 631789A

SVC CARB NF

USE 631790A

SVC CARB NF

SERVICE CARB

USE 631972A

SVC CARB NF

SERVICE CARB

USE 631794A

SVC CARB NF

USE 631795A

SVC CARB NF

31193

31194

USE 631893

USE 631855

USE 631226

USE 631226A

USE 631564

USE 630978

CHECK VALVE

FUEL FITTING

USE 630898

USE 630932A

USE 631893

USE 631790

USE 631790A

631197

631198

631201

631202

631205

631207

631208

631211

SERVICE CARBURETOR INFORMATION

(CONTINUED)

When the price list supersedes the original

carburetor you are ordering to a service

carburetor, you will need to identify the parts

not included on the service carburetor. To

determine these parts, turn to Division 5,

Section A in the Master Parts Manual or the

appropriate microfiche card listed under

carburetor." The information can be found

under the title "List of parts required to build a

complete carburetor from a standard service

carburetor."

The cross section shown below uses 631211

as the original carburetor number. The price

list supersedes that number to 631790A which

is a service carburetor. The items shown

following the number must be added to the

service carburetor to make it a complete

carburetor. Parts may be used from the

original carburetor if they are in good

condition. NEVER REUSE THE ORIGINAL

THROTTLE AND CHOKE SHUTTER

SCREWS.

NOTE

Since the mid 1980's Tecumseh Power has

discontinued the practice of establishing new

service carburetors.

LIST OF PARTS REQUIRED TO BUILD A COMPLETE CARBURETOR FROM A STANDARD SERVICE CARBURETOR

THIS LISTING REQUIRED ONLY WHEN ORIGINALCARBURETOR TO BE REPLACED IS NOT AVAILABLE.

NOTE WELL: IN ADDITION TO PARTS LISTED BELOW, ALL WILL REQUIRE:

EACH 650506 CHOKE SHUTTER SCREW

EACH 650417 IDLE REGULATING SCREW

EACH 630766 IDLE REGULATING SCREW SPRING

STANDARD THROTTLE THROTTLE CHOKE

CHOKE CHOKE DETENT

RETURN DETENT SPRING

ASSY. SHUTTER SPRING SPRING SCREW

ORIGINAL

CARB

SERVICE

SHAFT

ASSY.

RETURN

SPRING

SHAFT

CHOKE

PART NO. MFG. NO. CARB NO.

31177

31178

31211

148

134

162

169

168

190

191

196

631800A

631789A

631790A

631791

31384

631615

31384

631767

31868

31842

31841

630973

31869

31859

31868

630973

31837

631037

31837

31387

31837

631037

- -

630757A

- -

631238

631241

631256

631260

631262

632045

- -

631786

631789A

631799A

631715

31384

- -

31834

632045

USING THE COMPUTER PARTS

LOOKUP SYSTEM

Computer parts look up systems are fast, efficient and

allow you to use several different options when looking

up parts. If you know the part or manufacturing number

of the carburetor you can use that number to access

information to provide you with a parts list, artwork,

availability and pricing. One method of obtaining the

carburetor part number requires you to know the engine

model number. This is not always available and could

cause your customer some inconvenience having to

return home to retrieve that information from the engine.

If the customer has the carburetor along, you simply

need to locate the manufacturing number on the

carburetor and enter that number into the look up

system. The following steps will direct you through the

procedures needed to use either parts lookup system.

ALTERNATE LOCATION

FOR MANUFACTURING

NUMBER

CARBURETOR

DATE CODE

MANUFACTURING

NUMBER

PartSmart™

In this system the carburetor manufacturing number is considered an assembly. All assemblies are considered

models and can be found under the Model Inquiry selection on the main menu. Click on the Model Inquiry Icon. Type

the manufacturing number in the name box. This will automatically scroll the information on the screen. Click on the

bar listing the information you have selected to view artwork and a parts list.

FLOAT ADJUSTMENT PROCEDURE

FLOAT HEIGHT SETTINGS

TOOL 670377

RIM

Proper float setting will require the use of

Tecumseh Power tool part number 670377 or a 11/64"

drill bit. The procedure for setting the float height is as

follows. Remove the bowl gasket, then hold the

carburetor in the inverted position. Place the tool across

the carburetor body opposite and parallel to the float

hinge pin. Adjust the float height by bending the tab on

the float until it touches.

CARBURETOR REPAIR TIPS

SERVICING THE SEAT

Tecumseh engine carburetors are built with removable

seats made out of a material called VITON . These

seats are easily removed by using TecumsehPower tool

670377 or by bending the end of a paper clip or wire with

a 3/32" hook. Push the hook through the hole in the

center of the seat and remove it. Never reuse the old

seat, always replace with a new seat.

To install a new seat, make sure the seat cavity is clean,

then moisten the seat with a drop of oil to help it slide into

place. Position the seat with the grooved side of the seal

down and carefully push the seat into its cavity with a

5/32" flat punch until it bottoms out. TecumsehPower

tool 670377 can als operform this job.

INSTALLING INLET NEEDLE and FLOAT

Reinstall the inlet needle and the float into the

carburetor. Make sure the long end of the clip on the inlet

needle points toward the air intake (choke) end of the

carburetor.

INSTALLING THE FLOAT BOWL

Install the float bowl by placing the detent portion

opposite of the hinge pin. Make sure the deepest end of

the bowl is opposite of the inlet needlele. The bowl has a

small dimple located in the deepest part. The purpose of

this dimple is to minimize the chances of the float

sticking to the bottom of the bowl caused by stale fuel.

CARBURETOR REPAIR TIPS

(CONTINUED)

ALIGNMENT

NOTCH

SEAT RETAINING RING

(IF EQUIPPED)

FLOAT BOWL REPAIR - VECTOR AND SERIES 7

MAIN NOZZLE

To remove the float, take a needle nose pliers and grasp

the cross piece between the center leg and the pivot

point on the float. It is critical to pull the float straight out

so as not to break it. To install the float, place the float

hinge pin into the hinge slot on the float and press into

place in the bowl.

(

EMULSION TUBE)

NEEDLE & SEAT

“O” RING

MAIN NOZZLE

SPRING

Some bowls may also contain a clip or retaining ring,

used to hold the seat in place. This is pre-installed as

needed in the manufacturing process.

GASKET

ALIGNMENT

NOTCH

IDLE RESTRICTOR

To make assembly easy, an alignment notch has been

placed on the gasket and the bowl to guarantee proper

location of the gasket.

BRASS WASHER

HIGH SPEED

ADJUSTMENT

SCREW

ASSEMBLY OF MAIN MIXTURE SCREW

When reassembling the main mixture adjusting screw,

position the coil spring on the screw first, followed by the

small brass washer, then the rubber "O"ring seal.

“

O” RING

RETAINER NUT

SPRING

SMALL CHISEL

REMOVAL AND INSTALLATION OF WELCH PLUGS

PIERCE PLUG WITH TIP

To perform a proper cleaning, all welch plugs should be

removed to expose drilled passages. To remove the

welch plug, sharpen a small chisel to a sharp wedge

point. Drive the chisel into the welch plug, push down on

chisel, and pry out of position.

PRY OUT PLUG

WELCH PLUG TO BE

REMOVED

DO NOT ALLOW

CHISEL POINT

TO STRIKE

ABOUT 1/8” WIDE

CARBURETOR

BODY OR CHANNEL

REDUCER

A new welch plug should be installed bell-up as in the

illustration. Using a punch equal or greater than the size

of the plug, tap down onto plug. Do not dent or drive the

center of the plug below the top surface of the carburetor.

After installation of the welch plug, seal the outside edge

of the plug with nail polish to ensure that air will not enter

the mixing well, and that fuel will not leak out. Nail polish

is resistant to fuel. Using different colors for each

technician will identify the work of the previous repair

person.

SMALL CHISEL

FLAT END PUNCH

NEW WELCH PLUG

SAME OR LARGER

DIAMETER OF PLUG

SOME INLET FITTINGS

STRAINER

FUEL INLET FITTING

If necessary, this fitting can be removed by pulling and

twisting. Be sure to install in the same position as the

original. Some diaphragm carburetors have a strainer as

an integral part of the fitting. If the strainer is lacquered or

cannot be cleaned, replace the fitting. When installing a

fitting, insert the tip into the carburetor body. Coat the

exposed portion of the shank with Loctite grade A, then

press it in until the shoulder contacts the carburetor

body.

PRESS IN PARTIALLY

THEN APPLY LOCTITE

CARBURETOR REPAIR TIPS

(CONTINUED)

INLET FITTING REMOVAL

To remove a leaking or damaged fuel inlet fitting, use a

/4" bolt, 1/4" nut and 1/4" washer, along with a 1/2” nut.

Use a pliers or vise to remove the plastic part of the inlet

fitting. Tap the inside of the remaining metal portion of

the fitting using a 1/4"-20 tap. Place a 1/2” nut over the

fuel fitting (it may be necessary to guide one side of the

nut to seat it squarely to the carburetor). Next thread the

/4" nut on the bolt until it contacts the shank, add the

washer, and thread the bolt into the fitting until snug.

Tightenthe1/4"-20nut until the fitting is removed.

PROPER INSTALLATION OF CHOKE AND

THROTTLE PLATES ON Tecumseh ENGINE

CARBURETORS

CHOKE PLATE

Place choke plate into air horn of the carburetor. Make

sure the flat surface is facing down. Choke plates can

operate in both directions, however, each carburetor is

designed to operate only one way. Make sure it is

assembled properly for your engine.

FLAT DOWN

NOTE

Always use a new screw(s) when re-installing choke or

throttle shutter. NEVER reuseold screw(s).

THROTTLE

PLATE

THROTTLE PLATE SERVICE

THROTTLE LEVER

When installing the throttle plate on the 2 - 7 hp

carburetor, position the plate with scribe mark facing out

and in the 12 o'clock position.

NOTE

Make sure with all carburetors that binding does not

occur.

When installing the throttle plate on the 8 - 17 hp

carburetor, position the plate with scribe mark facing out

and in the 3 o'clock position.

NOTE

Make sure with all carburetors that binding does not

occur.

CARBURETOR REPAIR TIPS

(CONTINUED)

DIAPHRAGM CARBURETOR "F" DESIGNATION

If the carburetor has an "F" designation on the casting, it

will identify the installation sequence of the gasket and

diaphragm on the carburetor. "F" designated carburetors

have the diaphragm installed first then the gasket then

the cover. If there is no designation, the sequence is then

gasket, diaphragm and cover.

“F”

DESIGNATION

IDLE MIXTURE

SCREW

MAIN MIXTURE

SCREW

SERVICEABLE EMULSION TUBES

NOTE: NOT ON SERIES 7

AND VECTOR CARBS

Some carburetors use a serviceable emulsion tube

sealed with "O" rings on one or both ends. When

servicing these carburetors, the "O" ring(s) on the

emulsion tube needs to be removed. During the removal

of the tube the "O" ring on the venturi end of the tube may

remain stuck in the center leg of the carburetor. This "O"

ring must be removed and replaced to guarantee proper

“

O” RING ON

TO OF STEP

AIR BLEED HOLE

sealing and operation. To remove the tube bend a 90

hook in a paper clip or stiff wire. Reach in the venturi and

push the main nozzle emulsion tube out as far as

possible. Hook the wire into the air bleed hole and pull out

to remove. Make sure all "O" rings have been removed

and placed on the main nozzle emulsion tube before

re-installing the tube.

“

O” RING IN GROOVE

NO “O” RING ON SERIES 7

OR VECTOR CARBS

VECTOR AND SERIES7 EMULSION TUBESPRING

The emulsion tube spring in the Vector and Series 7

carburetor is used to put tension on the tube forcing it

towards the gasket. This seals the tube, preventing

unmetered air from entering the center leg. The proper

sequence is float bowl spring, tube, gasket and

carburetor body. To remove the emulsion tube, gently

grab the tube with a needle nose pliers and pull straight

out. If the tube is damaged or distorted replace it.

AIR BLEED HOLES

“O” RING IN GROOVE

MAIN NOZZLE AIR BLEED

TENSION SPRING

HOT RESTART

Occasionally, on engines equipped with the dual system

carburetor, some rich starting conditions have occurred

when the engine is warm. This can be corrected using the

white plastic spacer as shown and inserted in the center

leg of the carburetor. (Service # 632158). This spacer is

designed to reduce the amount of prime charge in the

main nozzle area for better starting under warm engine

conditions. It can only be used on Dual System

carburetors and does not lean out the carburetor mixture.

PLASTIC

SPACER

PRIMER BULB REPLACEMENT

PRIMER BULB IDENTIFICATION

EXTERNALLY

VENTED

INTERNALLY

VENTED

Care must be used when replacing carburetor primer

bulbs. Using the wrong primer bulb could cause hard

starting or non-starting problems. Currently,

Tecumseh engine use four different carburetor mounted

primer bulbs. To avoid problems, use the Master Parts

Manual for the correct application.

The five primer bulbs currently used feature two different

shapes; derby and stepped (or hour glass) and two

different venting types; internal or external.

INTERNALLY

VENTED

EXTERNALLY

VENTED

SEALING SURFACE

STEPPED PRIMER BULBS

A stepped primer bulb is used to force a charge of air into

the bowl through the atmospheric vent chamber. The

sealing surface as pictured prevents air from going back

into the air filter.

NOTE

Bowl prime systems require a good gasket seal on the

bowl or a low prime charge will be generated.

CAUTION

To avoid serious eye injury, wear

safety glasses or goggles when removing retainer.

To remove the primer bulb, grasp the bulb with a pliers,

pulling and twisting it out of its body.After removing the

primer bulb, the retaining ring must be removed. Use a

screwdriver to carefully pry the retainer out of the body.

Do not reuse old primer bulb or retainer.

After the primer bulb is removed, clean the primer

passages thoroughly.

Press the new bulb and retainer into position using a

deep reach socket.

NOTE

New primer bulbs come with a new retaining ring.

FUEL FILTER REPLACEMENT

Tecumseh engines use some form of filtration

prior to the carburetor. When a non-Tecumseh Power

tank is used, an in-line fuel filter between the tank and

carburetor is required. The filters use a 75 micron fibrous

paper to trap even the smallest particles of dirt while

maintaining the same flow rate. An arrow showing the

direction of flow is molded into the body of the filter to aid

in installation.

FUEL TANK FILTERS

All fuel tanks provided by Tecumseh Power have a 75

micron stainless steel filter screen molded right into the

tank over the fuel outlet. On TC series engines, a fuel

filter is located on the fuel line in the tank. These filters

can become restricted when foreign debris enters the

tank or when varnish and gum deposits form due to stale

fuel. Be sure to check these areas if you have a fuel flow

problem.

INTERNAL ATMOSPHERIC

VENT PASSAGE

INTERNAL ATMOSPHERIC VENT PASSAGE (FLOAT STYLE CARBURETOR). Some internally vented float

style carburetors will use a tygon tube within the air

cleaner. This tube must be present for the carburetor to

operate properly.

TYGON TUBE

TYGON TUBE LOCATION

TYGON TUBE

Carburetor Diagnosis

DAMAGED IDLE OR MAIN MIXTURE ADJUSTING

NEEDLES.

Mixture adjusting needles have a critical taper on the end

that is easily damaged from overtightening or abuse.

Check these parts if your carburetor is difficult to adjust.

WATER CONTAMINATION

Water contamination in the fuel system causes oxidation

and rust on the component parts. Once the oxidation

process starts it is irreversible; the carburetor must be

replaced.

GUM AND VARNISH

When the fuel is not completely drained from the system

during prolonged storage, the most volatile parts of the

fuel begin to oxidize and evaporate. This leaves the

crude portion of the fuel to remain and forms into resin,

gum, and varnish which will restrict and clog the fuel

system's passages.

FAILURE ANALYSIS

(CONTINUED)

WORN THROTTLE AND CHOKE SHAFTS

When operating in a dirty or sandy environment, these

areas can wear rapidly causing erratic performance.

Some shafts have been plated and dust shields have

been added to retard this wear. This is done based on the

application needs. Keeping these areas free from dirt

and grit will extend the life of the carburetor.

CRUSHED FLOAT

A crushed float will sink to the bottom of the carburetor

bowl holding the inlet valve open and causing the engine

to flood. This condition is caused either from water in the

fuel bowl freezing during extreme cold temperatures or

by blowing compressed air directly into the fuel inlet while

the carburetor is assembled.

WORN HINGE PIN

The hinge or hinge pin can wear excessively from dirt or

foreign matter in the fuel system. These worn areas will

cause a sticky or binding float which will result in either a

flooded or starved engine.

FAILURE ANALYSIS

(CONTINUED)

WORN NEEDLE AND SEAT

This is another area that can wear rapidly from dirt or

foreign matter in the fuel system. This condition creates

a poor seal at the seat area causing the carburetor to

flood or the engine to run rich. This can also cause the

needle to stick in the seat which will stop the flow of fuel.

WORN CARBURETOR BODY

If throttle shafts are plated, operation in a dirty or sandy

environment will tend to cause wear to the carburetor

body in the shaft area. Excessive wear in this area will

cause erratic engine performance or a binding throttle

plate. Again, to avoid this situation, clean these areas

regularly and keep them free from dirt and grit.

Tecumseh Power

ENGINES

& TRANSMISSIONS

Tecumseh Power International, LTD

Tecumseh Power Company

52-154 Commercial Road

900 North Street

Staines, Middlesex

Grafton, WI 53024

Phone: 262-377-2700

FAX: 262-377-4485

United Kingdom TW18 2QP

Phone: (44) 1 784-450785

Fax: 1 784-453563

www.TecumsehPower.com

Tecumseh Carburetor Parts

Provided by Barrett Small Engine

Tecumseh Carburetors

Form No. 695907 R12/07

Litho in U.S.A.