Fuel Pump: Description and Operation

FUEL PUMP

DESCRIPTION

Td6
The fuel system on Td6 vehicles features three fuel pumps. A primary fuel pump is mounted in the plastic fuel tank. This pump supplies fuel to the secondary pump mounted externally to the tank. The secondary pump supplies fuel to the high pressure Fuel Injection Pump (FIP) mounted on the engine.

V8
The fuel pump fitted on V8 vehicles is mounted in the plastic fuel tank, and supplies fuel at a constant 3.5 bar pressure to the fuel rail. The fuel rail distributes fuel evenly to each of the eight injectors.

OPERATION

Td6

Power Distribution
Feed from the positive battery terminal (C0192) is supplied to fusible link 5 of the passenger compartment fuse box (C0632) on an R wire. A constant battery feed is also supplied to the 100 A fuse located within the fuse holder (C1875) on an R wire. The 100 A fuse (C1878) provides a constant battery feed to the Engine Control Module (ECM) relay (C1895) on an R wire.

Fusible link 5 of the passenger compartment fuse box (C0588) is connected to fuse 15 of the rear passenger compartment fuse box (C2024) by an R wire. Fuse 15 provides a constant battery feed to the fuel pump relay, which is also located in the rear fuse box.

ECM Relay
The 100 A fuse located in the fuse holder (C1878) provides a constant battery feed to the ECM relay coil (C1895) on an R wire. The earth path for the relay coil (C1895) is controlled by the ECM (C0603) on an N wire. The energised ECM relay (C1895) provides a feed to fuse 51 of the passenger compartment fuse box (C0584) on an RW wire. Fuse 51 (C0585) supplies a feed to the fuel pump relay coil (C2022) on an RW wire.

Fuel Pump Relay
The fuel pump relay coil (C2022) receives a feed from fuse 51 of the passenger compartment fuse box (C0585) on an RW wire. The earth path for the relay coil (C2022) is controlled by the ECM (C0331) on a BP wire. The energised fuel pump relay provides a battery feed from fuse 15 of the rear fuse box to the primary (C0114) and secondary (C0205) fuel pumps on a pair of WU wires. Both pumps are earthed on N wires.

V8

Power Distribution
Feed from the positive battery terminal (C0192) is supplied to fusible link 2 and fusible link 5 of the passenger compartment fuse box (C0632) on an R wire. Fusible link 2 (C0591) provides a constant battery feed to the Engine Control Module (ECM) relay (C1895) on an R wire.

Fusible link 5 of the passenger compartment fuse box (C0588) is connected to fuse 15 of the rear passenger compartment fuse box (C2024) by an R wire. Fuse 15 provides a constant battery feed to the fuel pump relay, which is also located in the rear fuse box.

ECM Relay
Fusible link 2 of the passenger compartment fuse box (C0591) provides a constant battery feed to the ECM relay coil (C1895) on an R wire. The earth path for the relay coil (C1895) is controlled by the ECM (C0604) on an N wire. The energised ECM relay (C1895) provides a feed to fuse 51 of the passenger compartment fuse box (C0584) on an RW wire. Fuse 51 (C0585) supplies a feed to the fuel pump relay coil (C2022) on an RW wire.

Fuel Pump Relay
The fuel pump relay coil (C2022) receives a feed from fuse 51 of the passenger compartment fuse box (C0585) on an RW wire. The earth path for the relay coil (C2022) is controlled by the ECM (C0331) on a BP wire. The energised fuel pump relay provides a battery feed from fuse 15 of the rear fuse box to the fuel pump (C0114) on a WU wire. The fuel pump is earthed on an N wire.