The fuel system includes a mechanical fuel pump. It is mounted
on the lower, left-center of the engine cylinder block. The disposable
filter is located on the fuel pump body.
The fuel pumps are mechanically actuated by means of the fuel
pump rocker arm and an eccentric on the camshaft.
The 300 CID engines use either a Bendix Zenith one-barrrel
carburetor or a Holley 1904 or 1940 carburetor. These are covered in
detailed later in this section.
FIG. 2. Fuel Pump - Typical
DIAGNOSIS AND TESTING
A restricted fuel tank vent can cause low fuel pump pressure
Waiter and dirt that accumulate in the fuel tank can cause a
and volume and can result in collapsed inlet hoses or a collapsed fuel
restricted fuel line or filter and malfunction of the fuel pump or
carburetor Condensation, which is the greatest source of water
entering the fuel tank, is formed by moister in the air when it strikes
High or low pressure are the two most likely fuel pump troubles that
the cold interior walls of the fuel tank.
will affect engine performance Low pressure will cause a lean mixture
If the accumulation of dirt and water in the filter is excessive, the
and fuel starvation at high speeds and excessive pressure will cause
fuel tank should be removed and flushed, and the line from the fuel
high fuel consumption and carburetor flooding Dirt accumulation in the
pump to the tank should be removed be blown out.
fuel and air passages. improper idle adjustments, and Improper fuel
Air leakage in the fuel inlet line can cause low fuel pump
level are the major sources of carburetor troubles.
pressure and volume.
Low Fuel Pump Pressure
Diaphragm stretched or leaking.
Fuel line cracked or broken.
Fuel pump diaphragm spring is
Fuel pump valves seating
Cam eccentric worn or undersize.
Dirt in fuel tank and/or lines.
Excessive clearance between rod
Fuel tank sent restricted.
and fuel pump
Fittings loose or cracked
Fuel pump screen clogged.
High Fuel Pump Pressure
Diaphragm spring too strong
or improper spring.
Low Fuel Pump Volume
Fuel filter clogged.
Restriction in fuel supply line
with Normal Pressure
Fuel pump to carburetor inlet
to fuel pump.
line obstructed, crimped or
Fuel Pump Leaks
Diaphragm defective Fittings