Troubleshooting - Husqvarna 435 Workshop Manual

Troubleshooting

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
first, and so on.
Starting
Difficulty starting Adjust L screw
Air filter blocked
Choke not working
Worn choke pivot
Worn choke valve
Fuel filter blocked
Fuel line blocked
Piston ring seized
Blocked impulse channel
Carburettor Loose or faulty fuel pipe
leaking fuel 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
Flooding when Worn needle valve
engine not Needle valve set too high
running Needle valve assembly sticking
Idling (low rpm)
Adjust L screw
Will not idle
Leaking air intake hose (rubber)
Loose carburettor mounting
bolts
Loose or faulty fuel hose
Fuel filter 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
Idling too rich
Worn needle valve
Needle valve set too high
Worn needle valve lever
Leaking control diaphragm/cover
plate
Needle valve assembly sticking
54
– English
Idling (low rpm) (cont.)
Idles when L Worn needle valve
screw closed Leaking control diaphragm/cover
plate
Needle valve assembly sticking
Worn needle valve lever
Faulty diffuser jet
Idling uneven Fuel filter 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
L screw requires Fuel line blocked
constant adjust- Needle valve set too high
ment Needle valve assembly sticking
Leak in metering system (air
or fuel)
Leaking control diaphragm/cover
plate
Faulty diffuser jets
Crankcase leaking
Too much fuel at Needle valve set too high
idling Needle valve assembly sticking
Metering system damaged
Worn needle valve
Leaking control diaphragm/cover
plate
Metering system incorrectly
assembled