10 Series 4180 Powerhead
4.4 Carburetor
Condition Cause Remedy
Carburetor floods; engine stalls Inlet needle not sealing. Foreign
matter in valve seat or cone
damaged
Remove and clean or replace inlet
needle, clean fuel tank, pickup
body and fuel hose if necessary
Inlet control lever sticking on
spindle
Free off inlet control lever
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 new metering diaphragm
Inlet control lever too high (relative
to design position)
Set inlet control lever flush with
upper face of housing or bottom of
metering chamber
After more than five starting
attempts with choke shutter closed
Open choke shutter after no more
than five starting attempts
Poor acceleration Idle jet too lean Back off low speed screw slightly
Main jet too lean Back off high speed screw slightly
Inlet control lever too low (relative
to design position)
Set inlet control lever flush with
upper face of housing or bottom of
metering chamber
Inlet needle sticking to valve seat Remove inlet needle and clean
valve seat
Connecting bore to atmosphere
blocked
Clean bore
Diaphragm gasket leaking Fit new diaphragm gasket
Metering diaphragm damaged or
shrunk
Fit new metering diaphragm
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