Hi guys, I was driving my 1975 S Targa a fortnight ago and the car stalled going over a speedhump and wouldn't start again until I turned off the headlights (increasing the system voltage slightly).
I then parked it, went and did what I had to do, returned a few hours later and the car wouldn't start at all.
My fuel pump has always turned on with the key in 'Acc' rather than 'Ign' on, so it's really distinct (loud when everything else is silent) when it doesn't turn on. I couldn't get it to start at all and trailered the car home.
If I turn the ignition on, there is no voltage across the terminals that are supposed to feed the pump. Today I put a 12V car battery across the terminals of the pump and it fired into life no problem. So I think my initial problem is not the pump itself.
In the front compartment of the car, there are bays for fuel pump fuses and fuel pump relays, but they are empty - no electrical equipment there.
In the back there isn't much either, three fuse bays with two fuses. Two relay bays with one relay (pictured below) and one hard-wired connection which clearly isn't how it came from the factory! hahaha
I traced the fuel pump wires up into the engine bay and they went through this plug into the loom that runs down the LHS of the engine bay. Not actually sure whether they go forwards or backwards when they reach that loom.
I would like to get the car running again, maybe correct the wiring problem with the fuel pump switching with accessories also? Keen to hear what you pelicans have to say about that one - how it should be, or what works for you guys. I wouldn't rule out a separate circuit with its own switch, but maybe that's a bit sacrelidgeous on a Porsche.
The car is somewhat of a bitser, 3.0L SC motor etc, so I may need some gurus to tell me what is from what.
Appreciate any feedback!