Komatsu 114E-3 Series Shop Manual page 81

10 Structure, function and maintenance standard SEN00176-02
High pressure
pump
Main filter
Priming pump
Pre-filter
Fuel tank
Common rail fuel system
Common rail fuel system
The Common Rail Fuel System is a high-pressure
common rail injection system. A fuel rail is used to
store pressurized fuel for fuel injection. There are
four components that provide or receive input to the
electronic control module (ECM). The ECM powers
the electric fuel lift pump (located behind the ECM)
for approximately 30 seconds at key on to make
sure the fuel system is primed.
The normally open fuel pump actuator receives a
PWM signal from the ECM to open or close in
response to the signal from the fuel rail pressure.
The injectors have individual solenoids. The ECM
powers each injector individually to provide fueling
to each cylinder.
The high-pressure fuel pump can be divided into
four distinct assemblies. They are the fuel gear
pump, fuel pump actuator housing, cam housing,
and high-pressure fuel pump head. Fuel flows
through the gear pump to a 3-micron pressure side
filter. After the pressure side filter, fuel enters the
fuel pump actuator housing. The fuel pump actua-
tor housing includes an air-bleed fitting and the fuel
pump actuator.
Some fuel continuously returns to drain through the
air-bleed orifice fitting. Fuel that is metered through
the fuel pump actuator enters the high-pressure
fuel pump head where it is pumped to fuel rail pres-
sure and exits at the high-pressure outlet fitting.
11
114E-3 Series