TM 5-3895-379-23
THEORY OF OPERATION - CONTINUED
0003 00
FUEL SYSTEM
1.
General.
a.
When the engine is turning, fuel is pulled from the fuel tank through the fuel/water separator by the fuel lift pump.
The fuel lift pump sends the fuel at low pressure to the fuel filter. From the fuel filter, the fuel is sent to the fuel
injection pump. The fuel injection pump sends high pressure fuel through the high pressure fuel lines to the fuel
injector nozzles. The four fuel injector nozzles spray fuel into the cylinders of the engine. Any fuel not used by the
fuel injection pump is returned to the inlet side of the fuel filter.
b.
The engine is equipped with a cold start heater to warm fuel for starting the engine in cold weather.
2.
Fuel Tank. The fuel tank is part of the fuel/hydraulic tank assembly. The fuel tank is located on the right side of the
assembly. The fuel and hydraulic tanks are welded together, but are separate containers. The capacity of the fuel tank is
55 gal. (208 l) of diesel fuel or JP-8.
3.
High Pressure Fuel Lines. The high pressure fuel lines deliver fuel from the fuel injection pump to the fuel injector
nozzles.
4.
Fuel/Water Separator. The fuel/water separator separates any water from the fuel before reaching the fuel filter and the
engine. The water that is separated from the fuel collects at the bottom of a glass bowl located on the bottom of the sep-
arator. A drain valve is located at the bottom of the bowl and can be used to drain the water from the fuel/water separa-
tor.
5.
Fuel Lift Pump. The fuel lift pump delivers fuel to the fuel injection pump. The manually-operated lever primes the
pump by removing air and introducing fuel. Priming is needed after the fuel system has been opened or air is in the sys-
tem.
6.
Fuel Filter. The fuel filter removes foreign matter from the fuel before fuel enters the fuel injection pump.
7.
Fuel Injection Pump. The fuel injection pump forces high pressure fuel into the fuel injector nozzles. The fuel injection
pump is gear-driven from the crankshaft. The fuel injection pump needs fuel for lubrication. The precision parts are eas-
ily damaged. For this reason, the engine must NOT be started until the fuel injection pump is full of fuel that is free of
air.
8.
Fuel Injectors. The fuel injectors spray fuel into the cylinders of the engine.
9.
Cold Start Heater. The cold start heater is installed in the inlet manifold to heat inlet air in cold weather. When acti-
vated by operator controls, the current from the electrical wire causes the coil inside the heater to become very hot. A
small amount of fuel will flow through the heater as the engine is cranking.
0003 00-4
