Fuel System Components and Flow

The illustration identifies the components of the fuel system.

The engine is equipped with a cam-actuated lift pump. Fuel flow begins as the lift pump pulls fuel from the supply tank. The pump supplies low-pressure fuel (21-35 kPa, [3-5 psi]) to the fuel filter head, through the filter and then to the distributor injection pump.

The engines use distributor-type fuel pumps supplied by Robert Bosch.

The distributor pump builds the high injection pressures required for combustion, and routes the fuel through individual high-pressure fuel lines to each injector.

When the high-pressure fuel reaches the injector, the pressure 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.

FUEL SYSTEM SPECIFICATIONS
Maximum Allowable Restriction to Lift Pump with Dirty Filter - 95 mm Hg [3.75 in. Hg]

Maximum Allowable Return Line Restriction - 518 mm Hg [20.4 in. Hg]

Maximum Allowable Pressure Drop Across Fuel Filter - 21 kPa [3 psi]

Minimum Allowable Lift Pump Volume 0.75 liter [0.70 U.S. quart]

NOTE: Within 30 seconds at cranking speed.