SECTION Ill. MAINTENANCE OF THE FUEL INJECTION PUMP
6-7. GENERAL. See Figure 6-3, Figure 6-4, and Figure 6-5. The engine fuel system consists of a fuel pump, fuel filter
set, manual fuel shutoff valve, fuel lines and manifolds, and fuel injectors. The fuel system operates according to the
principle that the volume of fluid flow is proportionate to the fluid pressure, the flow time, and the size of the fluid
passages. The fuel pump is driven from the engine front gear train via an accessory drive unit which couples to the fuel
pump main shaft. The fuel pump main shaft operates an integral gear pump, upper and lower governor assemblies, and
tachometer shaft. Fuel enters the fuel pump through a fitting at the rear of the gear pump and is pumped to a filter in the
lower portion of the fuel pump housing. A pulsation damper attached to the gear pump contains a steel diaphragm which
reduces pressure pulses in the fuel system and a pressure valve, located in the gear pump, restricts the return flow of
fuel from the lower governor. Fuel then flows through the lower governor to the throttle shaft. The throttle provides a
means of manually controlling the engine at speeds above idle when maintenance or repairs require this type of
operation. During normal operation the throttle is locked in the fully open position and fuel passes to the electronic fuel
control actuator. The electronic fuel control actuator is an electromagnetic rotary solenoid valve, operated by a remote
electronic governor control. The actuator regulates fuel pressure and thereby regulates engine speed and horsepower.
Fuel leaving the electronic fuel control actuator flows through the upper governor to the shutoff valve located on top of
the fuel pump. The shutoff valve is electronically operated, and blocks the supply of fuel leaving the fuel pump; it is
actuated by an operator in the control room of the generator set selecting the STOP position of MASTER SWITCH S9.
The shutoff valve is also operated automatically by any one of the automatic shutdown systems in the generator set.
During normal operation, with the shutoff valve open, fuel leaves the fuel pump through a fitting on the shutoff valve.
6-8. FUEL PUMP INSPECTION. See Figure 6-4 and Figure 6-5. Inspect the fuel pump as follows:
Inspect the fuel supply and fuel discharge hoses (1 and 2, Figure 6-4) and fittings for damage and leakage.
Repair or replace damaged or leaking hoses and fittings.
Inspect for leakage at the joints between the pulsation damper assembly (10, Figure 6-5), gear pump assembly
(14), fuel pump housing (29), main shaft, cover, and governor assembly (31), and shutoff valve assembly (18).
Repair leaks by replacing gaskets or seals in accordance with paragraph 6-9.
Inspect the pump components for physical damage. Replace damaged components in accordance with
6-9. FUEL PUMP REPAIR. Repairs consist of replacing defective subassemblies, and on-engine adjustments. Test
and calibration procedures are contained in paragraph 6-11. Refer to troubleshooting, Chapter 2, Section 11 , to isolate
the problem, and replace the defective subassemblies as follows:
Disconnect the fuel supply and discharge hoses (1 and 2, Figure 6-4) from the gear pump assembly (14,
NO TAG) and shutoff valve assembly (18), respectively.
Remove the two electrical wires from the shutoff valve assembly (18).
Remove the two electrical wires from the actuator (4).
Remove electrical connector J1 (3, Figure 6-4) from the speed switch SS1/SS21SS3 (4), and remove the
speed switch SS1/SS2/SS3 from the main shaft, cover, and governor assembly (31, Figure 6-5).
Remove the capscrews (33), lockwashers (34), and washers (35), and remove the fuel pump (7, Figure 6-
4) from the accessory drive (6).
Remove the spider (19, Figure 6-12) and retain with the fuel pump (7, Figure 6-4). Discard the gasket (32,