TM 5-2420-230-24-2
Fuel System - General Information
B3.9 and B5.9 Series Engines
Page 5-4
Section 5 - Fuel System - Group 05
Fuel System Components and Flow - In-Line Fuel In-
jection Pump
A cam-actuated piston-style fuel transfer pump provides
positive fuel pressure to the fuel injection pump. Fuel flow
begins as the fuel transfer pump pulls fuel from the supply
tank. The system should have a prefilter or screen to re-
move larger contaminants from the fuel before reaching the
fuel transfer pump. The fuel transfer pump supplies low-
pressure fuel through the fuel filter head and filter, to the
fuel injection pump.
The Bosch in-line fuel injection pump is used on higher
rated '91 and '94 B Series automotive engines and '96
marine engines. The Nippondenso EP-9 was used on pre-
'96 higher horsepower marine B Series engines.
The Bosch P3000 fuel injection pump is used on higher
horsepower certified industrial engines and lower horse-
power '91 to '93 automotive engines.
Bosch "A"-type fuel injection pumps are used on lower
horsepower certified industrial engines.
The fuel injection pump builds the high injection pressures
required for combustion and routes the fuel through high-
pressure fuel lines to each injector.
All B Series engines use closed-nozzle, hole-type injectors.
When the high-pressure fuel reaches the injector, the pres-
sure lifts the needle valve against the spring tension to
allow fuel to enter the combustion chamber.
Any leakage past the needle valve enters the fuel drain
manifold.
On engines equipped with the Bosch in-line fuel injection
pumps, the manifold routes leakage from the injectors to
the inlet side of the fuel filter. On engines equipped with the
Nippondenso EP-9 fuel injection pump, the manifold routes
leakage from the injectors to the supply tank.
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