Fuel pump relay

[wild bill]

I've just had to replace my fuel pump and decided to replace the relay as well however I can't work out which one if the our it is. Does the relay stop the pump from constant priming?

 

Thx

[Paul Deslandes]

It depends on the age, engine and ECU. Early carb cars fuel pump was fed directly from the fuse box without a relay. If later converted to injection, then it was normal to add a relay to handle the extra current and/or to allow it to be controlled by the ECU.

 

For these and later injection cars the relay is controlled by the ECU which runs the pump for a couple of seconds after ignition 'on' and then cuts it off until the engine is cranked and starts.

 

The purpose is to allow the fuel system to prime sufficiently to start the engine but, if the engine stalls in an accident, the ECU detects the stall from the crank sensor and shuts off the pump to stop fuel potentially being pumped from a fractured fuel line.

 

So, to help identify the correct relay, let us know the year and engine type.

 

Paul

[wild bill]

Hi Paul

 

Thx. The car was originally a 1.8 K supersport from 1997. The relays are as per the original car af far as i know although it now has emerald ecu and 2.3 duratec.

 

Presumably i can take them out one at a time, turn the ignition and if i dont here the click on click off i'll be able to identify it?

 

Cheers