14 MS 311, MS 391
Condition Cause Remedy
Engine will not idle, idle speed too
high
Throttle shutter opened too wide by
idle speed screw LA
Reset idle speed screw LA
correctly
Oil seals/engine housing leaking Seal or replace oil seals/engine
housing
Throttle shutter does not close Replace throttle shutter and shaft
Air valve does not close Replace end cover with air valve.
Engine stops while idling Idle jet bores
or ports blocked
Clean the carburetor
Low speed screw too rich or
too lean
Reset low speed screw L correctly
Setting of idle speed screw LA
incorrect – throttle shutter
completely closed
Reset idle speed screw LA
correctly
Tank vent faulty Replace tank vent
Leak on fuel hose from tank to
carburetor
Seal connections or install new fuel
hose
Saw chain rotates at idle speed Engine idle speed too high Readjust with idle speed screw
LA (counterclockwise)
Clutch springs stretched or fatigued Replace the clutch springs or install
new clutch
Clutch spring hooks broken Replace the clutch springs
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