Fuel pump puzzler

[toast boy]

Hi all, after taking off my rocker covers to paint over the weekend I've got no fuel pump. Is there anything I could have disturbed in the engine bay that would stop it from working? I've got power to everything else it seems and the engine turns over but there's no whirring from the pump.

[The Beaver King]

toast boy said:

Hi all, after taking off my rocker covers to paint over the weekend I've got no fuel pump. Is there anything I could have disturbed in the engine bay that would stop it from working? I've got power to everything else it seems and the engine turns over but there's no whirring from the pump.

Would suggest running a voltmeter over the fuel pump to check for power.

Otherwise, I know that the pump goes quiet after initially priming, could there be a blockage or kink in the pipe that has confused the pump into thinking it's primed?

[toast boy]

I'm trying to test the pump at the minute but struggling as all of the jacks are at my workshop and the car is at my house. T
A blockage in the system is a possibility, I'll have an investigate now and see if that turns anything up.

Cheers.

[ketvrin]

toast boy said:

Hi all, after taking off my rocker covers to paint over the weekend I've got no fuel pump. Is there anything I could have disturbed in the engine bay that would stop it from working? I've got power to everything else it seems and the engine turns over but there's no whirring from the pump.

Hi Nathan

I cant see it being related TBH...

I dont suppose you have been under the dash and disturbed the fuel pump relay (yellow IIRC) have you ?

K

[toast boy]

Right, just squeezed myself underneath the car (not easy with no jack's or axle stands!) and the pump isn't getting any power. Next stop fuel pump relay...

[toast boy]

I've had the relay out and tested it, that's working fine. Does anyone have any ideas what else it could be?

[PompeyTim]

Mine has a brown wire in the nearside loom which is connected to a bolt on the throttle linkage assembly. This has to be removed before the rocker cover can be taken off.

I'm not sure if this is part of the standard factory loom or part of the alarm / immobiliser circuit.

Oops... just realised that I used the word 'standard' which is wholly inappropriate in TVR discussions

I seem to remember that when I failed to reconnect this wire some time in the dim & distant past I had similar symptoms so may be worth a look.

[kenpage]

pompey tim is spot on no wire connected no fuel pump

[toast boy]

Does it just connect to the bracket where the throttle cable attaches to the plenum chamber?

[kenpage]

as i remember yes if you turn the ign on before you attach it then attach by hand you should hear the pump start i think the wire is actually from the immobiliser

[toast boy]

Hmm, that shouldn't be it as my immobiliser was removed by an auto electrician when it decided not to work anymore. I'm running out of ideas here!

[v8s4me]

Have you checked the fuse? Might sound obvious but that's what caused my first breakdown call out.

[PompeyTim]

The ring terminal on the end of the cable goes under the head of one of the bolts which mount the throttle linkage assembly to the plenum.

[GreenV8S]

From your profile I guess you have a V6. I never really got into the V6 S electrics, but I know the V8S electrics quite well and perhaps the V6 is similar. On the V8S, the fuel pump is controlled (via the relay) by the ECU. The ECU gets an engine running signal from the distributor (low tension side). On the V8S this comes via a wire running along side the nearside rocker cover and through a dropping resister before joining the main engine loom. The dropping resister is normally close to the heater control valve.

If the V6 works in a similar way similar then I'd suggest you look for a signal wire from the dizzy to the ECU that you could have disturbed.

Oh, it might also be relevant that on the V8S this is derived from the switched ignition feed so anything that kills the switched ignition supply or inhibits the ignition low tension circuit would kill this signal.

[Gerald-TVR]

Might be a bit small but happy to email to anyone interested as a pdf

[toast boy]

Thanks for the replies, going to get out this morning with my proper tools and get diagnosing. With a bit of luck I'll be back soon with a running engine!

[Le TVR]

toast boy said:

I've had the relay out and tested it, that's working fine. Does anyone have any ideas what else it could be?

Do you mean you can hear it click or that there really are volts at the output pin??
Fuel pump relays often do one without the other....

[toast boy]

Le TVR said:

Do you mean you can hear it click or that there really are volts at the output pin??
Fuel pump relays often do one without the other....

It was working as it should, I connected it to a test lamp, activated it and the lamp came on. I'm almost certain it must be something in the engine bay that I've disturbed but can't figure out what it could be.

[Le TVR]

IIRC the fuel pump wiring on mine was attached to the top chassis rail on the LHS not far from the rocker cover/manifold area? Black/Yellow maybe?

Usual problem there is shorting and blowing fuses though.

[toast boy]

Fixed! After pulling out the fuse box and testing each fuse I found one of the 15 amp fuses had gone. Feel stupid for not testing all of them in the first place but incorrectly assumed that if the fuel pump fuse was fine it wasn't a fuse problem. Irritated that I wasted a lot of time yesterday but relieved that the head scratching is over!