Location
The fuel pump (1) is located on the front side of the engine below the fuel filter.
1 | Fuel pump (FP) |
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Task
The fuel pump (1) suctions the fuel out of the fuel tank via the fuel filter and supplies the single injection pumps for cylinders 1 to 6 (Y600 to Y605) with the required fuel quantity in all operating statuses of the engine.
Structure
1 | Fuel pump (FP) |
2 | Housing cover |
3 | Fuel outlet bore on the press side |
4 | Upper impeller (driven by the camshaft) |
5 | Lower impeller (driven by the upper impeller (4)) |
6 | Fuel connection (suction side) |
7 | Sealing ring |
8 | Thrust side transfer port |
9 | Intake side transfer port |
10 | Needle bearing |
11 | Pressure relief valve |
12 | Spring |
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Function
The upper impeller (4) is driven by the camshaft and drives the lower impeller (5) over the toothing. Because of the rotational movements of the top impeller (4) and the bottom impeller (5) and because of the design of the pump compartment, the fuel is suctioned via the fuel connection (6) and the intake side transfer port (9) and delivered along the inner wall of the pump to the pressure side fuel outlet bore (3).
The fuel is thus compressed until the fuel pressure required for the fuel low-pressure system is reached.
The required pressure that can be already be reached at the idle speed itself is determined by the opening pressure of the pressure relief valve (11).
After reaching the opening pressure for the relief valve (11), this opens and the fuel thrust side is short-circuited to the fuel intake side over a bypass channel so that the pressure cannot increase further.