THEORY OF OPERATION
WP 0004 00-17
ENGINE COMPONENTS (Continued)
Fuel Cutoff Solenoid:
An electrically-operated fuel cutoff solenoid
is contained within the fuel injection pump.
The solenoid is normally open.
A switch in
the vehicle driver's compartment actuates the
circuit to close the solenoid.
solenoid shuts off fuel delivery from the fuel
injection pump and stops the engine.
manually operated override shutoff is
provided to permit stopping the engine in the
event of an electrical failure.
Fuel flows from the vehicle fuel tanks through the primary fuel filter, backflow valve, engine-
mounted fuel supply pump, fuel/water separator filter to the fuel injection pump where it
passes through a final filter built into the pump. Excess fuel provides pump cooling as it flows
through the fuel injection pump hydraulic heads and is returned to the fuel tanks.
Primary Fuel Filter - The replaceable-element type primary
fuel filter is mounted on the right front of the engine.
equipped with a constant bleed orifice and drain line that
removes a metered amount of fuel and returns it to the main
fuel tank through the fuel injector nozzle drain lines.
continuous drain, from the bottom of the filter, removes water
that has been filtered from the fuel by the primary fuel filter
Fuel/Water Separator Filter - a replaceable-element type
filter, it is mounted on the left front of the engine.
purpose filter, the fuel/water separator filter first removes
emulsified water from the fuel and then removes solid
particles not trapped previously by the primary fuel filter.
The fuel/water separator filter consists of two outer
elements (coalescer elements for removing water) a center
element, which is the final fuel filter (down to 5 microns),
and a water collection chamber with two water-sensing