Stihl 029, 039 - 2.6 Fuel System

STIHL 029, 039 12
Note: For machines with automatic choke see 11.6.2.
Condition Cause Remedy
Carburetor floods; Inlet needle not sealing. Remove and clean or replace
engine stalls Foreign matter in valve seat or inlet needle,
cone damaged clean fuel tank, pickup body and
fuel line if necessary
Inlet control lever sticking on Free off inlet control lever
spindle
Helical spring not located on Remove inlet control lever
nipple of inlet control lever and refit correctly
Perforated disc on diaphragm Fit new metering diaphragm
is deformed and presses constantly
against inlet control lever
Inlet control lever too high Set inlet control lever flush
(relative to design position) with bottom of metering chamber
Poor acceleration Idle jet "too lean" Back off low speed adjusting
screw slightly
(see Carburetor Adjustment)
Main jet "too lean" Back off high speed adjusting
screw slightly
(see Carburetor Adjustment)
Inlet control lever too low Set inlet control lever flush
(relative to design position) with bottom of metering chamber
Inlet needle sticking to valve Remove inlet needle, clean
seat and refit
Connecting bore to atmosphere Clean bore
blocked
Diaphragm gasket leaking Fit new diaphragm gasket
Metering diaphragm damaged Fit new metering diaphragm
or shrunk
Engine will not idle, Throttle shutter opened too wide Reset idle speed adjusting screw
idle speed too high by idle speed adjusting screw correctly
2.6 Fuel System