TROUBLESHOOTING
Chainsaw troubleshooting chart
The different faults that can occur on the chainsaw are
divided into four groups as follows. Within each group
possible operating faults are listed to the left while the
probable fault alternatives are listed to the right.The most
likely fault is listed first, etc.
Starting
Idling (low speed) (continued)
Idles with closed L-screw
Worn needle / needle tip
Difficult to start
Adjust the L-screw
Air filter blocked
Leaking diaphragm / coverplate
Control system sticking
Worn lever arm in the control
system
Choke does not work
Worn choke axle
Worn choke valve
Blocked fuel filter
Blocked or broken fuel line
Faulty diffuser jet
Piston ring seized
Blocked impulse channel
Uneven idling
Blocked fuel filter
Blocked fuel line
Leaking intake hose (rubber)
Loose carburetor mounting
Worn throttle valve axle
Loose throttle valve screw
Worn throttle valve
Control system sticking
Leaking control system (air or
fuel)
Carburetor leaks fuel
Loose or faulty fuel pipe
Hole in diaphragm
Worn needle / needle tip
Control system sticking
Control system set too high
Leaking control system (air or
fuel)
Loose cover on carburetor
pump side
Worn center knob in control
system
Hole in diaphragm
Floods when engine is
not running
Worn needle / needle tip
Control system set too high
Control system sticking
Leaking diaphragm / coverplate
Leaking crankcase
L-screw requires
Blocked fuel line
constant adjustment
Control system set too high
Control system sticking
Leaking control system (air or
fuel)
Idling (low speed)
Leaking diaphragm / coverplate
Faulty diffuser jet
Leaking crankcase
Does not idle
Adjust the L-screw
Leaking intake hose (rubber)
Loose carburetor mounting
Loose or faulty fuel pipe
Blocked fuel filter
Too much fuel when idling Control system set too high
Control system sticking
Blocked fuel line
Damaged control system
Worn needle/needle tip
Leaking diaphragm / coverplate
Incorrectly fitted controlsystem
Tank ventilator blocked
Throttle valve axle stiff
Throttle wire sticks
Defective throttle return spring
Bent valve axle stop
Faulty diffuser jet
Too rich idling
Adjust the L-screw
Worn needle/needle tip
Control system set too high
Worn lever arm in the control
system
Leaking diaphragm / coverplate
Control system sticking
–
TROUBLESHOOTING
High speed
Acceleration and retardation
Will not run at full
throttle
Adjust H-screw
Blocked air filter
Does not accelerate
Adjust the L-screw
Adjust the H-screw
Tank ventilator blocked
Blocked fuel filter
Blocked fuel line
Blocked air filter
Tank ventilator blocked
Blocked fuel filter
Loose or faulty fuel pipe
Impulse channel leaking
Blocked impulse channel
Cover on carburetor’s pump
side is loose
Blocked fuel line
Loose or faulty fuel pipe
Blocked impulse channel
Cover on carburetor’s pump
side is loose
Faulty pump diaphragm
Leaking intake hose (rubber)
Loose carburetor mounting
Control system set too low
Damaged control system
Incorrectly fitted control system
Leaking diaphragm / cover plate
Control system sticking
Blocked muffler
Faulty pump diaphragm
Leaking intake hose (rubber)
Loose carburetor mounting
Control system set too low
Incorrectly fitted control system
Control system sticking
Faulty diffuser jet
Blocked muffler
Engine stops when
throttle released
Adjust the L-screw
Adjust the H-screw
Low power
Adjust H-screw
Tank ventilator blocked
Blocked fuel filter
Impulse channel leaking
Blocked impulse channel
Cover on carburetor’s pump
side is loose
Faulty pump diaphragm
Control system set too high
Control system sticking
Faulty diffuser jet
Too rich acceleration
Adjust the L-screw
Adjust the H-screw
Blocked air filter
Faulty pump diaphragm
Blocked air filter
Control system sticking
Leaking control system
Faulty pump diaphragm
Faulty diffuser jet
(air or fuel)
Control system incorrectly
assembled
Loose diaphragm
Hole in diaphragm
Leaking diaphragm / coverplate
Will not “four stroke”
Tank ventilator blocked
Blocked fuel filter
Trouble shooting methods
Blocked fuel line
Loose or faulty fuel pipe
Impulse channel leaking
Blocked impulse channel
Cover on carburettor’s pump
side is loose
In addition to faults given in the above schematic, trouble
shooting can be carried out on a specific component or
specific chainsaw system. The different procedures are
described in respective sections and are as follows:
Faulty pump diaphragm
Leaking intake hose (rubber)
Loose carburetor mounting
Control system set too low
Leaking control system (air or
fuel)
Control system incorrectly
assembled
Loose diaphragm
1
. Pressure testing the carburetor.
2. Pressure testing the crankcase
and cylinder.
3. Pressure testing the decompression
valve.
4. Checking of the chain brake.
Hole in diaphragm
Leaking diaphragm / cover plate
