Stihl FS 50 Service Manual

11Series 4144 Components FC, FS, KM
4.4 Carburetor
Condition Cause Remedy
Carburetor floods; engine stalls Inlet needle not sealing
– foreign matter in valve seat or
cone
Remove and clean the inlet needle,
clean the carburetor
Inlet control lever sticking on
spindle
Check inlet control lever, replace if
necessary
Helical spring not located on nipple
of inlet control lever
Remove the inlet control lever and
refit it correctly
Perforated disc on diaphragm is
deformed and presses constantly
against the inlet control lever
Fit a new metering diaphragm
Metering diaphragm deformed Fit a new metering diaphragm
Poor acceleration Setting of low speed screw too lean Check basic carburetor setting,
correct if necessary
Setting of high speed screw too
lean
Check basic carburetor setting,
correct if necessary
Inlet needle sticking to valve seat Remove inlet needle, clean and
refit
Diaphragm gasket leaking Fit new diaphragm gasket
Metering diaphragm damaged or
shrunk
Fit a new metering diaphragm
Tank vent faulty Replace tank vent
Leak in fuel hose between tank and
fuel pump
Install new hose

Stihl FS 50 Specifications

General

Engine Displacement	27.2 cc
Power Output	0.8 kW
Engine Type	2-stroke
Shaft Type	Straight
Starter System	Recoil
Overall Length	147 cm
Vibration Level	4.5 m/s²