Husqvarna 3120 XP Workshop Manual - Page 40

TROUBLE SHOOTING Trouble shooting schematic Faults that can develop on the chain saw are divided into four groups as follows. In each category, possible malfunctions are shown on the left, with a list of possible faults on the right. The most probable fault is given first and so on. Starting Idling (low rpm) (cont.) Difficult starting Adjust L-screw Air filter blocked Choke not working correctly Worn choke shaft Worn choke plate Fuel filter blocked Fuel line blocked Piston ring seized Blocked impulse channel Carburettor leaking fuel Loose or faulty fuel pipe Hole in diaphragm Worn needle valve/needle Control system sticking Control system set too high Leak in control system (air or fuel) Loose cover on carburettor pump side Flooding when the engine is not running Worn needle valve Control system set too high Control system sticking Idles when L-screw closed Idling uneven Worn needle valve/needle Leaking control diaphragm/ cover plate Control system sticking Worn throttle lever Faulty diffuser jet Fuel filter blocked Fuel line blocked Leaking manifold Loose carburettor mounting Worn throttle valve shaft Loose throttle valve screw Worn throttle valve Control system sticking Leak in throttle system (air or fuel) Control diaphragm centre knob is worn Hole in diaphragm Leaking control diaphragm/ cover plate Crankcase leaking Idling (low rpm) Will not idle Adjust L-screw Leaking manifold (intermediate) Loose carburettor mounting Loose or faulty fuel pipe Fuel filter blocked Fuel line blocked Fuel tank breather blocked Throttle shaft and lever stiff Throttle cable sticking Defective throttle return spring Bent throttle lever shaft stop Faulty diffuser jet Idling too rich Adjust L-screw Worn needle valve/needle Control system set too high Worn throttle lever Leaking control diaphragm/ cover plate Control system sticking L-screw requires constant adjustment Too much fuel at idling Fuel line blocked Control system set too high Control system sticking Control system (air or fuel) Leaking control diaphragm/ cover plate Faulty diffuser jet Crankcase leaking Control system set too high Control system sticking Control system damaged Worn needle valve Leaking control diaphragm/ cover plate Control system incorrectly assembled 40 - English