FUEL PUMP
DESCRIPTION
General
The fuel pump is an electric submersible pump located in the fuel tank and controlled by the
ECM.
OPERATION
Power supplies
Fuse 2 of the under bonnet fuse box (C0571) supplies a permanent battery feed to the inertia
switch (C0123) on a N wire. A NS wire connects the inertia switch (C0123) to the switch
contacts of the fuel pump relay (C0157) in the engine management relay module.
Fusible link 4 (C0570) in the under bonnet fuse box supplies a permanent feed to the ignition
switch (C0028) on a NP wire. When the ignition switch is in position II or III, power is supplied
from the ignition switch on a BY wire to fuse 14 (C0099) in the passenger compartment fuse
box. Fuse 14 (C0585) supplies the feed to the coil of the fuel pump relay (C0154) and to the
ECM (C0159 on MPi MEMS 1.9 and VVC MEMS 2J models, C0634 on MPi MEMS 3
models) on W wires.
General
The fuel pump relay is energised by the ECM for a few seconds after the ignition is switched
to position II and then continuously during cranking and once the engine has started. The
ECM energises the fuel pump relay by connecting an earth to the P (VVC MEMS 2J models)
or BP wire (MPi MEMS 1.9 and MEMS 3 models) between the fuel pump relay (C0154) and
the ECM (C0159 on MPi MEMS 1.9 and VVC MEMS 2J models, C0634 on MPi MEMS 3
models).
When the fuel pump relay is energised, the fuel pump (C0114) is supplied with battery power
from the switch contacts of the fuel pump relay (C0157) on a WP wire. The fuel pump
(C0114) is earthed on a B wire connected to an earth header (C0550).
In the event of an impact, the inertia switch opens and disconnects the electrical supply to
the fuel pump relay to prevent operation of the fuel pump.

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