Troubleshooting - Husqvarna 390XP Workshop Manual

Troubleshooting

20.1 General troubleshooting
The different faults which can occur on the chainsaw are
divided into four groups. 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.
Starting
Difficult to start Air filter blocked
Choke does not work
Worn choke axle
Worn choke valve
Blocked fuel filter
Blocked fuel line
Piston ring is stuck
Blocked impulse channel
The carburettor Loose or faulty fuel hose
Hole in diaphragm
leaks fuel
Worn needle/needle tip
Control system sticking
Control system set too high
Leaking control system
(air or fuel)
The cover on the carburettor
pump side is loose
Floods when the Worn needle/needle tip
Control system set too high
engine is not run-
Control system sticking
ning
Idling (low speed)
Does not idle Leaking inlet hose (rubber)
Loose carburettor mounting
Loose or faulty fuel hose
Blocked fuel filter
Blocked fuel line
Tank ventilator blocked
The throttle valve shaft is inert
Throttle stay is binding
Defective throttle return spring
Bent valve axle stop
Faulty diffuser jet
Too rich idling Worn needle/needle tip
Worn lever arm in the control
system
Leaking diaphragm/cover plate
Worn needle/needle tip
Leaking diaphragm/cover plate
Worn lever arm in the control
system
Faulty diffuser jet
52 - English
20 Troubleshooting
High speed
Uneven idling Blocked fuel filter
Blocked fuel line
Leaking inlet hose (rubber)
Loose carburettor mounting
Worn throttle valve axle
Loose throttle valve screw
Worn throttle valve
Leaking control system
(air or fuel)
The control system's centre
knob is worn
Hole in diaphragm
Leaking diaphragm/
cover plate
Leaking crankcase
L screw requires Blocked fuel line
Leaking control system
constant adjustment
(air or fuel)
Leaking diaphragm/cover plate
Faulty diffuser jet
Leaking crankcase
Too much fuel at Worn needle/needle tip
idle speed Leaking diaphragm/
cover plate
Will not run at full Blocked air filter
Tank venting clogged
throttle
Blocked fuel filter
Blocked fuel line
Loose or faulty fuel hose
Impulse channel leaking
Blocked impulse channel
The cover on the carburettor
pump side is loose
Faulty pump diaphragm
Leaking inlet hose (rubber)
Loose carburettor mounting
Control system set too low
Damaged control system
Control system incorrectly as-
sembled
Leaking diaphragm/cover plate
Control system sticking
Blocked muffler