Troubleshooting
The various faults that can affect a chainsaw are divided into four groups. In each group the likely symp- toms 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) |
|
|
|
Will not idle | Adjust L screw |
| 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 |
|
|
Idling too rich | Adjust L screw |
| Worn needle valve |
| Needle valve set too high |
| Worn needle valve lever |
| Leaking control diaphragm/ |
| cover plate |
| Needle valve assembly |
| sticking |
|
|
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 | Needle valve set too high |
adjustment | 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 |
|
|
10 – English
