3-03
Fuel System
3-03
SYMPTOM
PROBABLE CAUSE
Fuel Pump Leaks Oil
Fuel pump retaining bolts
Mounting gasket defective.
loose.
Fuel Tank and/or Inlet
Fuel tank vent restricted.
Line Hoses Collapsed
Flooding or Leaking
Cracked carburetor body.
Ruptured accelerating pump
Carburetor
High fuel level or float setting.
diaphragm (where applicable).
Fuel inlet needle not seating
Excessive fuel pump pressure.
properly or worn needle and/
or seat.
Hard Starting
Improper starting procedure
Incorrect fuel pump pressure.
causing a flooded engine.
Restrictions or air leaks in
Improper carburetor fuel level.
the choke vacuum or hot air
Improper idle adjustments.
passages
Sticking or incorrectly seating
Dirty air cleaner element.
fuel inlet needle.
Stalling
Incorrect idle fuel mixture.
Carburetor icing (cold, wet
Engine idle speed too slow.
or humid weather).
Dirt. water or ice in fuel
Incorrect throttle linkage
filter
adjustment to carburetor.
Fuel lines restricted or
Clogged air bleeds or idle
leaking air.
passages
Fuel tank vent restricted
Defective fuel pump.
Leaking intake manifold or
Excessive looseness of
carburetor gaskets.
throttle shaft in bore(s)
of throttle body.
Rough Idle
Incorrect Idle mixture
Idle air or fuel passages
adjustment.
restricted.
Idle adjusting needles(s)
Idle discharge holes restricted.
grooved, worn. or otherwise
Idle discharge holes not in
damaged.
proper relation to throttle plate.
Idle air bleeds restricted.
Excessive dirt in air cleaner.
Accelerating pump discharge
High or low float setting.
check valve not seating
properly.
Poor Acceleration
Poor acceleration complaints
Incorrect accelerating pump
fall under one of three
stroke adjustment.
headings: the engine is
Accelerating pump fuel inlet
sluggish on acceleration.
or outlet valve not seating
the engine stalls when
Restriction in the accelerating
accelerated, or the engine
pump discharge passage.
hesitates or develops a flat
Air leak at the accelerating
spot when accelerated. Poor
pump cover caused by a
acceleration is caused by
defective gasket or warped
either an excessively lean
pump cover
or rich mixture on acceleration
and/or defects of Improper
adjustments in the ignition
system.
A LEAN MIXTURE CAN BE
A RICH MIXTURE CAN BE
CAUSED BY
CAUSED BY:
Low fuel pump pressure.
Excessive fuel pump pressure.
Sticking fuel inlet needle.
High fuel level or float setting
Low fuel level or float setting.
Fuel inlet needle not seating
Restriction in main fuel passage.
properly or worn needle and/or
Air leak between the carburetor
seat.
and the manifold caused by
Excessively dirty air cleaner.
loose mounting bolts or
Incorrect accelerating pump
defective gasket.
stroke adjustment.
Air leak at the throttle shaft
Restricted air bleeds.
caused by a worn throttle shaft.
Worn or damaged main metering
Accelerating pump diaphragm
jet.
defective.
Accelerating pump outlet valve
not seating properly.
