Fuel pump not working?

[Damien_Griff]

Evening All,

Hope everyone is well.

First time posting here, my name is Damien and I have a pre-cat (4.3) Griffith. Today I've encountered a strange problem and I wonder if one of you knowledgeable folks would be kind enough to lend some guidance please?

So today I fitted a battery brain to the Griff as there is no power available where the car is kept. In order to run a feed to the 'engine on' lead on the battery brain, I pulled a fuse in anticipation of fitting a fuse tap wire, and tested the fuse holder with a meter to ensure that it was dead when the ignition was off. However, when I replaced the fuse, there was no life from the fuel pump - the 2-3 second buzz it normally makes when the ignition is first switched on was conspicuously absent! The fuse is good (incidentally it was fuse 12 - Ignition and ECU), as is the fuse for the pump itself. I didn't pull every single fuse but those I could see/ put a meter on were all good - none of the ones that seem relevant have failed. There is a clicking relay (I'm guessing for the pump but am not 100% sure) when the ignition goes on. My initial thought was, maybe a connection had broken behind the fuse holder but with the fuse back in, I put a meter on the ignition coil and this was receiving a current with the ignition on, which suggests the circuit beyond the fuse is also good.

At the point this failure happened, the only other thing I'd touched was to remove the glove box to give a bit more space whilst delving down into the footwell - prior to this the car had started and driven fine. I didn't touch anything else electrical, aside from unbolting the battery box to slide it (and the ECU/ birds nest of wiring that lives on top of the battery) forward to reach the fuse panel. With the glove box out, I did wonder if it could have been the inertia switch but am not really sure what this does...

Whilst doing all the above, I hadn't actually fitted the battery brain so can rule that out (although it's fitted now, at least I had one win today!) as the cause. To cut a long story medium-length, I'm now stumped! Does anyone have any ideas of what could be the problem please?

Any assistance you can offer gratefully received!

All the best,

Damien

[Loubaruch]

You may have disturbed something while moving the relay fuse panel but a logical approach is the best method to pinpoint the problem.

This may help: http://www.bertram-hill.com/fuel-pump-schematic.ht...

I would start by running wires from the battery direct to the fuel pump to rule that out and then working your way back through the circuit.

Other possible problems:

The multi way connector by the near side B post, behind the carpet as it can get damp.
The relays hanging in the footwell
The black multiway plug/socket in the footwell
The immobiliser
A poor contact on the ECU plug/socket
Dont be surprised if during your investigation the fault dissapears as is the way with intermittent faults
Best of luck

[Belle427]

I would check that inertia switch as that seems the most logical thing to have been disturbed.

[NicBowman]

Tricky thing wiring. Alarm / immobiliser has control of the fuel pump. To add to the possibilities. Recent experience with a TVR Griff I was considering buying had the same, appeared to be fuel pump, was the alarm. Best of luck.

Nic

[Tyre Smoke]

But rhe click of the relay would indicate it isn't the immobiliser/alarm.

[Aussie John]

There is a fuel pump fuse in the birds nest wiring on my 94 Griff.

[Damien_Griff]

Many thanks all for your replies, really appreciated and I'm back on the road as a result! Loubaruch hit the nail on the head, it must have been a dodgy connection somewhere in the birds nest of footwell wiring, after a good poke around and checking all connections were tight the problem has gone away (for now, anyway!). Frustrating not to know what exactly it was, but I guess that's the nature of intermittent faults!

Thanks again all.

Cheers

Damien

[lancepar]

If the relay is getting very warm, this is why...........



They don't like water in them.

[Loubaruch]

Very pleased that you are back and running but as a precaution I would look at the relay bases, the black multi plug/socket and the ECU plug/socket for any signs of corrosion and give them all a good clean.

[Damien_Griff]

Loubaruch said:

Very pleased that you are back and running but as a precaution I would look at the relay bases, the black multi plug/socket and the ECU plug/socket for any signs of corrosion and give them all a good clean.

That's a good shout, many thanks for that - a job for the next tinkering day!

Cheers

Damien

[Steve_D]

I would also take some time on your 'tinkering day' to generally twist, pull and otherwise pummel the loom in the footwell as you may either have a break or an otherwise intermittent connection somewhere. A favourite is the blue coloured 'loopback' connector in that part of the loom.

It is basically 4 busbars in one connector type body. Just about everything important passes through it.
In no particular order.
• Injectors
• MAF
• Main ECU relay
• Tune resistor
• ECU earths
• Fuel pump relay
• Coil
• Common grounds for MAF, fuel temp, coolant temp, TPS
• Ignition supply to ECU.
• Plus others (20 in all)

Imagine a female pinned connector with all the wires for one function (say ignition switched +12) all in a line along the connector then a tin plated strip of ‘fingers’ is pushed into the connector joining all those pins as one. In this connector there are 4 strips 2 with 4 fingers and 2 with 6 fingers.

Steve

[Damien_Griff]

Steve_D said:

I would also take some time on your 'tinkering day' to generally twist, pull and otherwise pummel the loom in the footwell as you may either have a break or an otherwise intermittent connection somewhere. A favourite is the blue coloured 'loopback' connector in that part of the loom.

It is basically 4 busbars in one connector type body. Just about everything important passes through it.
In no particular order.
• Injectors
• MAF
• Main ECU relay
• Tune resistor
• ECU earths
• Fuel pump relay
• Coil
• Common grounds for MAF, fuel temp, coolant temp, TPS
• Ignition supply to ECU.
• Plus others (20 in all)

Imagine a female pinned connector with all the wires for one function (say ignition switched +12) all in a line along the connector then a tin plated strip of ‘fingers’ is pushed into the connector joining all those pins as one. In this connector there are 4 strips 2 with 4 fingers and 2 with 6 fingers.

Steve

Many thanks Steve, that's a good shout. Gotta love classic British vehicle wiring!!!