TM 5-3805-258-24-1
FUEL SYSTEM
SYSTEMS OPERATION
valve (7) in the large piston closes and the pressure of
the fuel below the check valve increases. Fuel now
flows through the outlet check valve. A part of the
fuel goes through outlet (4) and the remainder goes
to the area above small piston (3).
FUEL TRANSFER PUMP SCHEMATIC (UP STROKE)
1. Bypaaa valve. 2. Pumping spring. 3. Small piston. 4.
Outlet. 5. Inlet check valve. 6. Push plate. 7. Pumping
check valve. 6. Outlet check valve. 9. Large piston. 10.
Push rod.
FUEL TRANSFER PUMP SCHEMATIC (DOWN STROKE)
1. Bypaaa valve. 2. Pumping spring. 3. Small piston. 4.
Outlet. 5. Inlet check valve. 6. Push plate. 7. Pumping
check valve. 8. Outlet check valve. 9. Large piston. 10.
Push rod.
As the large piston moves down, fuel from the fuel
tank is pulled through inlet check valve (5) into the
area between the large and small piston. The pump is
now ready to start a new cycle.
Bypass valve (1) controls the outlet pressure of the
fuel. If the fuel pressure goes beyond 170 to 280 kPa
(25 to 40 psi), the bypass valve opens and fuel flows
to the inlet of the pump.
OIL FLOW FOR FUEL PUMP AND GOVERNOR
Oil from the side of the cylinder block goes to
support (9) and into the bottom of front governor
housing (4). The flow of oil now goes in three differ-
ent directions.
A part of the oil goes to the rear camshaft bearing
in fuel pump housing (5). The bearing has a groove
around the inside diameter. Oil goes through the
groove and into the oil passage in the bearing surface
(journal) of camshaft (7). A drilled passage through
the center of the camshaft gives oil to the front
camshaft bearing and to the thrust face of the cam-
shaft drive gear. Drain hole (6) in the front of fuel
pump housing (5) keeps the level of the oil in the
housing even with the center of the camshaft. The oil
returns to the oil pan through the timing gear
housing.
Oil also goes from the bottom of the front governor
housing through a passage to the fuel pump housing
and to governor servo (2). The governor servo gives
hydraulic assistance to move the fuel rack.
The remainder of the oil goes through passages
to the rear of rear governor housing (3), through air
fuel ratio control (1) and back into another passage
in the rear governor housing. Engines that do not
have an air fuel ratio control have a cover with an
oil passage to complete the oil flow. Now the oil goes
into the compartment for the governor controls.
Drain hole (8) keeps the oil at the correct level. The
oil in this compartment is used for lubrication of
the governor control components and the oil is the
supply for the dashpot.
The internal parts of the governor are lubricated
by oil leakage from the servo and the oil is thrown by
parts in rotation. The flyweight carrier thrust bear-
ing gets oil from the passage at the rear of the
camshaft.
Oil from the governor returns to the oil pan
through a hole in the bottom of the front governor
housing and through passages in the support and
cylinder block.
3-6
