Relays and Fuel Pump power

[niva441]

To celebrate it's first run this year the wedge has decided to breakdown. Fortunately it waited until I got home. The excitement of actually running was too much for it and it's decided not to start again. Either that or it like being stuck in the garage and found the outside world frightening.

I've managed to track the fault down to there being no fuel pressure due to the fuel pump not running. However I've manage to wire up the pump independantly and that runs fine. So I think the problem is in the wiring down to the pump.

Since mine is one of the wonderful black wired cars, where does the fuel pump wiring start? I haven't managed to find the Fuel pump in the Wedge Bible wiring diagram.

Also related to this I'm trying to work out which relays are which? I've 7 relays clustered together under the bonnet in the front right corner. They are arranged in a block of 4, next to a block of 2 and a single relay.

The block of 2 are part of the headlamp system and one of the block of 4 is the starter, other than that I'm stuck. Any further clues would be much appreciated.

Thanks

Todd

[wedg1e]

Take the air filter box off an get someone to stick their hand in and lift the flap. This should cause one of the relays to click. Identify that relay.
There's also a common failure spot down in the front left-hand corner of the engine bay, where the fuel pump feed wire meets the main harness. There's a connector there somewhere that has a habit of corroding...

[Geddy]

Don't know if it would help but I have a circuit diagram for my 81 2.8, produced by buzzing out the circuits. I also have traced the wire routing, etc but I havent put that in computer form yet. EMail if you're still stuck

[grahamw48]

niva441 said:

To celebrate it's first run this year the wedge has decided to breakdown. Fortunately it waited until I got home. The excitement of actually running was too much for it and it's decided not to start again. Either that or it like being stuck in the garage and found the outside world frightening. I've managed to track the fault down to there being no fuel pressure due to the fuel pump not running. However I've manage to wire up the pump independantly and that runs fine. So I think the problem is in the wiring down to the pump. Since mine is one of the wonderful black wired cars, where does the fuel pump wiring start? I haven't managed to find the Fuel pump in the Wedge Bible wiring diagram. Also related to this I'm trying to work out which relays are which? I've 7 relays clustered together under the bonnet in the front right corner. They are arranged in a block of 4, next to a block of 2 and a single relay. The block of 2 are part of the headlamp system and one of the block of 4 is the starter, other than that I'm stuck. Any further clues would be much appreciated. Thanks Todd

Mine doesn't like to start when hot, and I've got someone coming to have a good look over the engine and fuel system on Tuesday.

However, she also sometimes just cuts out, at any time really.
The fix for that is twiddling one of the row of fuses (mine is the black wiring model too). I think it's the white one near the bottom.
Result - instant starting.

Check to see if you have the red charging light on, on the dash.
If not, try the fuses, as above.
The light will re-appear, and the car will start.

Hopefully someone can explain to me (simpleton that I am ) why this should occur.

[wedg1e]

Graham: you should have said you were having problems, I could have taken a look at it.

The probability is that the prehistoric fuse holder is tarnished and/or not gripping the fuse tightly enough. It can also be the fuse itself that's tarnished. I forget what fuses are on the Tasmin though I don't recall there being one for the ignition circuit and can't check without a rummage in the loft (and Julie's asleep!)

You can buy a new 12-way fusebox from VWP; it has screw terminals instead of the dreaded push-on Lucas type that TVR used, though still takes those dreadful ceramic fuses - £17.37 + the usual ripoff.

The inner wing was a fairly stupid place to put the fuses and relays anyway...

[grahamw48]

Thanks Ian - didn't like to pester you.

As soon as there is warm sun on my back, I plan to have a sort out under the bonnet. A new board would be a good idea.

I'm hoping the mobile mechanic will be able to give me a few clues as to why the car feels so gutless.

It may be as well simply to replace it with a more modern 2.9 - but need to consider the manifolds.

I just missed some nice Cerbera wheels on ebay today.
Mustn't go too mad on the bidding.

[niva441]

Sorted

After tracing the wiring back to the engine bay I found I had 12v at the fuel pump. Obviously it couldn't have been a very high quality 12v.

I got suckered by the nice shiny bolts the local TVR dealer used when they replaced the fuel filter and a few other jobs. When I took these off, the fuel pump earthing point was rotten.

All I need to do now is work out why only one headlight raises. How do you manually raise the lights on an early wedge? The access holes mentioned in the Wedge bible don't seem to be there.

>> Edited by niva441 on Saturday 23 April 18:16

[wedg1e]

It's a problem if the access holes are missing! This seems to crop up quite often; I find it hard to believe the factory kept forgetting to cut them so maybe these are cars that have had new noses and the fitters didn't think (or weren't aware) of cutting the holes?
I suppose you could cut some yourself, if you knew where they needed to be...