TM 5-2420-230-24-2
B3.9 and B5.9 Series Engines
Fuel System - General Information
Section 5 - Fuel System - Group 05
Page 5-3
Fuel System - General Information
Fuel System Components and Flow - Distributor-Type
Fuel Injection Pump
Most of the engines will be equipped with a cam actuated
fuel transfer pump. Two types of fuel transfer pumps are
available for distributor-type fuel injection pumps: 1) A
diaphragm-style fuel transfer pump and 2) a piston-style
fuel transfer pump. The piston-style fuel transfer pump is
offered as an option. Fuel flow begins as the fuel transfer
pump pulls fuel from the supply tank though a mandatory
prefilter. The fuel transfer pump supplies low-pressure fuel
to the fuel filter head, through the filter, and then to the
distributor injection pump.
The distributor pump builds the high injection pressures
required for combustion and routes the fuel through indi-
vidual high-pressure fuel lines to each injector.
When the high-pressure fuel reaches the injector, the pres-
sure lifts the needle valve against the spring tension to let
the fuel enter the combustion chamber.
Any leakage past the needle valve enters the fuel drain
manifold. The fuel drain manifold routes controlled venting
from the distributor injection pump and leakage from the
injectors back into the fuel tank.
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