Auto Electrician needed!

[Davemg]

The inertia switch is a good point... have you found it and is it tripped....

Two wires... what else isn't working?

I had a similar problem and just rewired the car. There comes a point where it's quicker - and about 3 weeks.

[Flyingtiger]

I know kit car wiring doesn't follow any normal conventions, including the laws of physics, but "usually" a red wire is a permanent live (connected to the battery, often via a fuse) & a black wire is a switched live (from the ignition, again often via a fuse).

I would expect the fuel pump relay to have four wires:-
A red from a fuse in to the relay (providing permanent 12v).
A (insert colour here) out to the inertia switch & on to the fuel pump.
A black in (ignition live to the relay switching circuit).
An earth (often brown) to complete the switching circuit.

So when you turn on the ignition, 12v from the ignition switch closes the main contacts allowing 12v from the red wire to pass through to the inertia switch & on to the fuel pump.

Of course the inertial switch could be wired into any of the four wires & it'll still work.

Good luck!

Thanks Fury!
Starting to think whoever did my wiring defied the laws of physics and was colour blind!
Fuel pump has one red and one black wire, I assumed red=sw live, black=earth. red wire. This seems to go against the "usual" as well as the tiger wiring diagram which show white/red/white - aah!
Hoping to get back on it later, lastly, leaned on the dash whilst trying to manoeuvre my hulk and now the rear lights and internal lights come on with ignition on! I have ordered some new wires already!
tbc ...

[Flyingtiger]

The inertia switch is a good point... have you found it and is it tripped....

Two wires... what else isn't working?

I had a similar problem and just rewired the car. There comes a point where it's quicker - and about 3 weeks.

thats the worry, i can't find anything else not working?! tried to by pass the inertia switch to make sure but no joy. Its a mess under there, reckon your suggestion may be best! new wires have just arrived!

[Flyingtiger]

Latest update: sorry it's a long one!
Many slipped discs and head scratching i have worked this out so far:

As you can see, a nice rainbow of colours So disregard my previous about red wires, that was a separate issue with the lights which is now sorted.

Seems this is an intermittent fault and i am wondering if it is either relay or ignition related. Powered up the car, started working again so I was able to work out the circuit. Went out of a drive today, 10 min in it died. Multimeter at the ready, no power at either(87), also no power at white (86). I jumped a wire from the fuse to the red fuel pump wire (87), pump worked but car wouldn't start. I then moved the jumper to white (86), the relay clicked a couple of times and hey presto, all good! Disconnected jumper wire and car stayed running. 5 min later it died again. . Jumper wire re-connected and left connected, car was good, 30 min drive and no problem, obviously when i shut down the pump still ran so had to disconnect the jumper.

Sorry chaps, several questions:
When things are working correctly, i notice when i switch the ignition on, the fuel pump runs for about 10 secs, then stops until engine start. Do the fuel pumps have a timer/pressure cut out, or is there another circuit controlling this somewhere?
Can the relays partially fail, giving these problems? Struggling to find the same Wehrle replacement, as 87a pin is not used can i use a normal make or break relay? Big variation in price even if you avoid fleabay chinese ones. Any recommendations?

I'm considering running a new switched live to (86 white) and replacing the relays but any help/advice greatly appreciated. Trying to get to Stoneleigh next w/e so want to get this sorted!
Learned a lot and now have a better understanding of relays - thanks for your previous posts!
Still need to work out where some of the wires go - both (85); the 2 green (87) and the other red with the fuel pump(87).

[Matth93]

It looks like a fairly standard relay just make sure you get one that can take at least the same ampage through it as the old one. Yes it could be a relay problem they do fail sometimes they can overheat and burn the contacts inside or the windings inside can break down