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no power to fuel pump
In message <firstname.lastname@example.org> Audinamx@aol.com writes:
> ... I checked the '87-'88 5kTQ wiring diagram in the Bentley. I was
> surprised to find that the fuse (S13) is actually in the circuit AFTER
> the fuel pump relay! This means that there is no protection for the
> FP relay itself if the output is shorted to ground before the fuse ...
Only a couple of inches of wire, though. They're right next to each other.
> If I had this problem, I'd open up the FP relay and check the relay
> contacts, burnishing them if they looked like they were oxidized/
> pitted. If I could scrounge up another relay I'd probably test with
> that for a while. If that didn't do the trick, I'd run the ECU output
> diagnostics [activated by inserting a fuse in the top of the FP relay
> when the ignition is on but the engine isn't running] and make sure
> that the ECU was controlling the FP relay properly. The diagnostic
> procedure works on the '87-88 5kqs ... actually it probably works
> on all 5kTs with the MC engine ... and is well described in Bentley.
The diagnostics run everything reliably - he has an ECU shutdown problem.
My initial thoughts are the flywheel timing senders and the Hall sender.
There's a finite chance that it's simply a defective ECU ...
Hard to think of something that could inhibit starting but permit the car to
run once the engine is turning over.
Committee Member, UK Audi [ur-]quattro Owners Club