RRC 92 3.9efi fuel pump issues

Hoping here I can find a solution!

ive a 92 EFi RRC, these past 2 years completed near a full rebuild. Problem being getting no fuel out of the fuel pump, which is new. I energised the car today but no fuel from pump? I’m getting 4.7 volts on the loom at the pump which I think is the gauge, but, cannot ignite the fuel pump! History, all electrics were disconnected during rebuild during welding etc. Everything else working but just can’t get fuel out of the pump! Wiring diagrams only show +ve and Earth, yet I have three wires on the loom plug, plus the Earth. Questions - to test the pump which wires on the loom connector would prove the pump with a 12v battery to test (blue, black and green), is there a reset process on the ECU? (btw the isolator switch is not in the trip position). How do I hot wire, on which pins to test the pump in the tank is actually not faulty? Any other ideas? Completely baffled... all ideas welcomed!

hope this forum site my salvation after 2 years of hard work!

Have you got a copy of RAVE? Pretty sure it covers your year.

Hopefully someone like @ukadamwest or @Saint.V8 will be along shortly.

As a wild stab in the dark, does the lift pump have a relay somewhere you could bridge to activate it? You'll probably hear it and then you could collect some fuel if you remove the fuel pipe somewhere, possibly if there's a fuel filter along it?

I’ve intercepted the flow line at both the water filter and at the injection head, no fuel. Equally taken off the fuel line at the pump source under the rear floor, no fuel. Hence unsure how to validate test the pump isn’t faulty. There are 3 lines in the loom plus and Earth to the pump head: not sure which two are the live to trigger the pump into action.

You might check the fuel pump ground...
It is located on the left side rear...or USA
Models driver side...on the frame above the wheel...
Also you can power the pump with separate power source to verify it is working...
The relay for the fuel pump is under the passenger seat ... again USA model...
I added these pages just in case...
Also on the past when my fuel pump acted up
It was a simple fix of just unplugging it and then plugging it back in...crazy stuff..

You need to know from the wiring diagram which pump lead powers the pump, which is earth & which are for the fuel level sender as it's a combined unit.
If the colours differ from the vehicle loom look at the terminal positions in the two connectors.
Once you know that you can apply 12v from a battery & see if the pump runs.

ETA. Are your pump wires solid colours or do they have stripes of another colour?
And what colours are the wires on the vehicle loom at the plug the pump connects to & do they have stripes?

This is what I have for 1992 fuel system....taken fro mthe original 1992 electrical troubleshooting manual

Just noticed this one. Fuel pump playing up is something I have come to live with. Things to check:
1: Fuel pump relay, if it is stuck or just dead then no fuel. Maybe try swapping with the main efi power relay.If you listen when you switch on the ignition you should hear the relays click, first is efi power, then fuel pump and then I think abs relay.
2: Check connector plugs - at pump under the cover in the boot but also under floor, passenger side just under the chassis, the cable should be easily found tucked under there with a connector.
3: Is the pump original? if a replacement I found the connector adapter plays up if it has one of the old round shape connectors, the "new" rectangular plugs should be ok but I found mine sometimes needs a wiggle to get it back to working.

Worst case would be an ecu fault but that should put the efi warning light on.

HTH

The fuel pump relay is controlled/switched by the EFI ECU, I don’t expect that the 3.9 RR is any different from the Disco 3.9. disco.

Folks - first and foremost Thankyou for all your advice! Poor connector on the new pump, the wiring from the pump to the loom, the new connector in the pump housing had not sat properly into the pump connector! Hours of trawling and metering and swapping relays, but then testing noticed the terminal perturbing from the seat in the pump housing connector! She’s up and running sweet... but now ABS pump problems, very noisy pump running constantly and no brakes.... one step forward! Watch out for the next post on ABS troubleshooting!

great forum - thank you all!

222ASH said:

Folks - first and foremost Thankyou for all your advice! Poor connector on the new pump, the wiring from the pump to the loom, the new connector in the pump housing had not sat properly into the pump connector! Hours of trawling and metering and swapping relays, but then testing noticed the terminal perturbing from the seat in the pump housing connector! She’s up and running sweet... but now ABS pump problems, very noisy pump running constantly and no brakes.... one step forward! Watch out for the next post on ABS troubleshooting!

great forum - thank you all!

Click to expand...

Bleed the brakes would be my first port of call.

Grrrrrr said:

Bleed the brakes would be my first port of call.

Click to expand...

I agree ... bleed the brakes...
Also check the pump where the fluid enters...from the reservoir...
They can get clogged with gunk...