FUEL SYSTEM
TM 5-3805-263-14&P-2
The 8N7005 Fuel Injection Nozzle can not be
disassembled and no adjustments can be made.
SYSTEMS OPERATION
FUEL TRANSFER PUMP
The fuel transfer pump is a two-piston pump that
is moved by a cam (eccentric) on the camshaft for the
fuel injection pump. The transfer pump is located on
the right side of the fuel injection pump housing.
When the camshaft turns, the cam lifts push rod
(10) up. The push rod lifts large piston (9), push
plate (6) and small piston (3). As the pistons move
up, inlet check valve (5) and outlet check valve (8)
close. Pumping check valve (7) in the large piston
opens and fuel goes through the holes in the bottom
of the large piston and fills the passages and chamber
between the bottom of the large piston and outlet
check valve (8). As small piston (3) moves up, the
pressure of the fuel above the piston increases and
flows out of the pump through outlet (4).
As the camshaft continues to turn, the cam lowers
push rod (10) down. Pumping spring (2) pushes
small piston (3), push plate (6) and large piston (9)
down. When the piston moves down, inlet check valve
(5) and outlet check valve (8) open. Pumping check
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).
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.
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