Section 2.5 Fuel Pump

Section 2.5
Fuel Pump

The fuel system consists of the following component:‪

  • Barnes positive displacement type fuel pump

The positive displacement gear-type fuel pump is shown in the following illustration. See Figure "Positive Displacement Gear Type Fuel Pump" .‪

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Figure 1. Positive Displacement Gear Type Fuel Pump

The fuel pump transfers fuel from the supply tank to the Electronic Unit Pumps (EUP). The pump circulates excess fuel supply through the EUPs. This purges the air from the system and cools the EUPs. The unused fuel returns to the fuel tank via the fuel return line.‪

The fuel pump is directly mounted to the cylinder block.‪

The small relief valve vent permits the fuel oil in the inlet side of the pump to lubricate the relief valve at its outer end. This eliminates the possibility of a hydrostatic lock. Pressurized fuel contacts the relief valve through the passage to head of the relief valve and provides for relief of excess discharge pressures. Fuel re-enters the inlet side of the pump through the passage to head of the relief valve when the discharge pressure is great enough to move the relief valve back from its seat. Part of the relief valve may be seen through the passage to head of the relief valve. The gear teeth vent cavity provides escape for the fuel oil that is squeezed out of the gear teeth as they mesh on the discharge side of the pump. Otherwise, fuel trapped at the root of the teeth would tend to force the gears apart, resulting in undue wear on the gears, shafts, body, and cover.‪

Section 2.5.1
Replacement of Fuel Pump

Repair of fuel pump is not permissible. Remove and replace faulty fuel pump. See Figure "Flowchart for Replacement of Fuel Pump " .‪

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Figure 2. Flowchart for Replacement of Fuel Pump

Section 2.5.2
Removal of Fuel Pump

To remove the fuel pump, perform the following steps:‪

  1. Disconnect the fuel lines from the fuel pump inlet and outlet openings.
  2. Remove the three fuel pump attaching bolts, and withdraw the pump from the fuel pump drive shaft. See Figure "Fuel Pump Assembly and Related Components " .
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    1.Flange Head Bolt‪

    4.Fuel Pump Assembly‪

    2.Gasket‪

    5.Outlet Fuel Fitting‪

    3.Inlet Fuel Fitting‪

    Figure 3. Fuel Pump Assembly and Related Components


Series 55 Service Manual - 6SE55
Generated on 10-13-2008