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3.9 RRC fuel pump


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Hi All

I have acquired a RRC to ressurect.

It has the "Discovery style" fuel pump in the plastic fuel tank, and there is no power feed going to it.

I have traced the cable back to the inertia switch under the passenger seat. This switch is ok, but there is now power to either of the cables running to it.

Where does the Blue / white wire go to? The purple ans white appears to go to the fuel pump.

THe fuse appears to be OK, and the relay under the drivers seat is clicking.

Any ideas welcomed.

I can't find my old haynes manual so am groping in the dark a bit at the moment.


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Those blue/white wires run between the ECU/Relays and the intertia switch, they run right between the front seats, towards the rear, under the carpet.

Somewhere in the run of those wires are a couple of crappy bullet or spade connectors, they've been trod on by passengers for nearly 20 years, had luggage dropped on them, and the conditions below the carpet and sound deadening are usually a bit damp. Often as not it's those connectors that go high resistance. I had to cut them out of the loom on mine and apply some good old fashioned solder.

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The pump is driven by a relay but the wire then goes back to the dash and through the fuse box (Fuse 18) before going to the inertia switch and then to the tank.

A number of possible problem areas.

I believe the ECU gives a couple of second of pump run when you turn on the ignition but don't know what condition has to exist for it to stay running. You will need to know this before you can do any realistic tests. On the 3.5 flapper system the flap had to be open (air coming in) before the pump runs but I don't know how it works on the hotwire.


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  • 2 weeks later...

Does anyone know what volts you should get to the fuel pump? Is it 12 volts?

The reason I ask is because I've had no petrol system since a rather deep ford....... :blink:

On a few occasions a friend on mine has tried to get it working with no luck but what he did note was the fuel pump is getting around 5 volts to it & he said it should be getting 12 volts.

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Thats exactly what we thought.

Any ideas then chaps about what could be wrong?

Dirty connections anywhere in the circuit.

Dirty connections at the relay would be high on the list.

When you tested and found 5V, was that testing back to a known good earth? If not, and it was tested to the existing tank earth, then this could also be the culprit and would have been at the top of my list if you were just saying the pump was not working.


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