User Manual

The fuel pump assembly consists of a low-pressure
transfer pump and a high-pressure fuel injection
pump. The pump assembly is driven from a gear in
the front timing case at one a half times the engine
speed. The fuel injection pump (1) has one plunger
that are driven by a camshaft. The stroke of the
plunger is fixed but the volume of fuel that is provided
by the fuel injection pump is controlled by the suction
control valve.
The injector will use only part of the fuel that is
delivered by each stroke of the pistons in the pump.
The suction control valve (2) for the fuel injection
pump is controlled by the ECM. This maintains the
fuel pressure in the fuel manifold (rail) at the correct
level. A feature of the fuel injection pump allows fuel
to return to the tank continuously.
The fuel injection pump has the following
operation:
• Generation of high-pressure fuel
The fuel output of the fuel injection pump is controlled
by the ECM in response to changes in the demand of
fuel pressure.
Shutoff
The engine shuts off by preventing the electronic unit
injectors from injecting. The ECM then closes the
suction control valve to prevent the pressure in the
fuel manifold (rail) from increasing.
28 UENR0623-02
Engine Operation
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