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