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54 – English
Troubleshooting
Starting
Idling (low rpm)
Idling (low rpm) (cont.)
Adjust L screw
Leaking air intake hose (rubber)
Loose carburettor mounting
bolts
Loose or faulty fuel hose
Fuel lter blocked
Fuel line blocked
Fuel tank vent blocked
Throttle valve pivot stiff
Throttle pushrod sticking
Defective throttle return spring
Bent throttle stop
Faulty diffuser jet
Adjust L screw
Worn needle valve
Needle valve set too high
Worn needle valve lever
Leaking control diaphragm/cover
plate
Needle valve assembly sticking
Will not idle
Idling too rich
8.1 Troubleshooting
The various faults that can affect a chainsaw are divided into four groups. In each group the likely
symptoms are given on the left and possible causes are listed on the right. The most likely faults are given
rst, and so on.
Worn needle valve
Leaking control diaphragm/cover
plate
Needle valve assembly sticking
Worn needle valve lever
Faulty diffuser jet
Fuel lter blocked
Fuel line blocked
Leaking air intake hose (rubber)
Loose carburettor mounting
bolts
Worn throttle valve pivot
Loose throttle valve screw
Worn throttle valve
Needle valve assembly sticking
Leak in metering system (air
or fuel)
Metering system centre knob
is worn
Hole in diaphragm
Leaking control diaphragm/cover
plate
Crankcase leaking
Fuel line blocked
Needle valve set too high
Needle valve assembly sticking
Leak in metering system (air
or fuel)
Leaking control diaphragm/cover
plate
Faulty diffuser jets
Crankcase leaking
Needle valve set too high
Needle valve assembly sticking
Metering system damaged
Worn needle valve
Leaking control diaphragm/cover
plate
Metering system incorrectly
assembled
Difculty starting
Carburettor
leaking fuel
Flooding when
engine not
running
Adjust L screw
Air lter blocked
Choke not working
Worn choke pivot
Worn choke valve
Fuel lter blocked
Fuel line blocked
Piston ring seized
Blocked impulse channel
Loose or faulty fuel pipe
Hole in diaphragm
Worn needle valve
Needle valve assembly sticking
Needle valve set too high
Leak in metering system (air
or fuel)
Loose cover on carburettor
pump side
Worn needle valve
Needle valve set too high
Needle valve assembly sticking
Idles when L
screw closed
Idling uneven
L screw requires
constant adjust-
ment
Too much fuel at
idling