Ford Sierra Manual

Fuel pump - testing
Fuel and exhaust systems - fuel injection / Fuel pump - testing


1 If the fuel pump is functioning, it should be possible to hear it УbuzzingФ by listening under the rear of the vehicle when the ignition is switched on. Unless the engine is started, the fuel pump should switch off after approximately one second. If the noise produced is excessive, this may be due to a faulty fuel flow damper (not fitted to 2.0 litre DOHC models). The damper can be renewed by unscrewing it from the pump outlet union.

2 If the pump appears to have failed completely, check the appropriate fuse and relay, and where applicable check the state of the fuel pump inertia cut-off switch as follows.

3 The inertia cut-off switch is fitted to all models from mid-1986 onwards, and can be found behind the passenger compartment left-hand side trim panel on Hatchback and Estate models up to the 1987 model year (see illustration).

7.3a Fuel pump inertia cut-off switch - pre- 1987 SOHC Hatchback and Estate
7.3a Fuel pump inertia cut-off switch - pre- 1987 SOHC Hatchback and Estate models

A Activated mode (fuel cut-off) B Normal mode (fuel flowing) C Trim panel access hole

The location of the switch for all other models is in the spare wheel well (see illustration).

7.3b Fuel pump inertia cut-off switch location (arrowed) under spare wheel
7.3b Fuel pump inertia cut-off switch location (arrowed) under spare wheel

The switch incorporates a reset button, which should normally be in the depressed position. Check the position of the reset button before assuming that a fault exists in the fuel pump.

4 To test the fuel pump, special equipment is required, and it is recommended that any suspected faults are referred to a Ford dealer.


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