[Author Prev][Author Next][Thread Prev][Thread Next][Author Index][Thread Index]

no power to fuel pump

In message <971015034337_2067059452@emout01.mail.aol.com> 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.

 Phil Payne
 Committee Member, UK Audi [ur-]quattro Owners Club