Fuel pump not running.... again! Help please.

[dbv8]

Since i fitted a high flow fuel pump some 6 months and a few thousand miles ago it has blown 2 fuses.

A few weeks ago i went to a rolling road session then drove another 100+ miles to Stratford. I turned the engine off to pay at the gate to Shakey and the car wouldnt restart. All fuses were ok and i pressedthe inertia switch and the car restarted.
Im not sure wether it was the enertia switch or resetting the imobiliser that did the trick.

Yesterday the car wouldnt start at the car wash. Same procedure, checked the fuses, played with the inertia switch... no start.

I got help and my other car to tow it home but first swapped the fuel pump fuse 1 last time and the car fired up but cut after a few seconds and wouldnt restart.

Its in the garage now grounded .
Any ideas?

[scotty_d]

Its intermittent which makes me think the immobiliser they are a right pain. Does the fuel pump prime at all now?

[dbv8]

No, no fuel pump noise and no pressure at the gauge.
I was kinda hoping it wasnt the immobiliser as i guess it wont be a simple fix.

The last thing i need is my fuel pump cutting on the drag strip when i have a load of nitrous running.... MELTDOWN!
I will be getting a fuel pressure transducer fitted to cut the nitrous system just in case.

[pwd95]

Have you tried setting the alarm off & re setting it a few times?

[dbv8]

I will do tonight.
Hope to get a few ideas together today.

[scotty_d]

YHM did not want to post this on the open fourm.

[dbv8]

scotty_d said:

YHM did not want to post this on the open fourm.

Cheers for that. Sounds like a plan that may suit me. Hope it cures my problem.

[GreenV8S]

It will be a simple electrical problem and as long as it keeps happening you shouldn't have any trouble tracking it down.

To start with I suggest you make up a fused wire to take 12V straight from the battery to the fuel pump +ve. If the pump runs with that connected you know the pump itself is OK; you also know you can now get the car home regardless of the problem.

Next locate the fuel pump relay and identify the terminals on it. When you connect 12V to the output terminal, the pump should run. If it doesn't, there is a fault between the relay socket and the pump. usually this circuit goes via the inertial cut-off switch. If you can clear the symptoms by resetting the switch, you know the switch needs attention. Mine started playing up and when I opened it up found it was full of rust.

If that isn't the problem then test whether you have +12V to the relay socket main power input and also switched ignition to the coil circuit. If not, it's a problem with the fused supply or ignition supply.

[dbv8]

GreenV8S said:

usually this circuit goes via the inertial cut-off switch. If you can clear the symptoms by resetting the switch, you know the switch needs attention. Mine started playing up and when I opened it up found it was full of rust.

I think this will be my first check tonight.
I got one of those sneaky feelings.
Otherwise i will check as you have suggested.
Thanks

[lwt]

I am just wading through this problem for the 2nd time. I thought it was the inertia switch first time round. This time I have traced it to the yellow wire running from the fuel pump to the connector break behind the door panel just behind the passenger seat. Try running +12v to it and then put a 55w bulb in place of the pump (both around 5A load) and generally pull, twist & waggle the yellow wire and see if the light flickers. I found a broken wire (inside the insulation) that made the intermittent connection. Unfortunately the spade connector is not the standard 1/4" (6.35mm) and all I could do for a new connector was to carefully tweak a 1/4" one to fit. Hardly ideal but it will have to do until I can source the right one. I used a few tie-wraps as insurance to make sure it cannot work its way loose.


Ian.

[dbv8]

Update.
It appears to have been down to a dodgy connection on the 'common' to the inertia switch.
This has been sorted so fingers crossed no more fuel pump cutouts!