Porsche Repair: 1986 porsche turbo fuel pumps non opp, fuel pumps, loose end

Question
I have checked and replaced relays for pump but they will only work if I bypass relays. Was told that a relay in engine compartment (boost relay) could also shut off pumps. I think I lost a ground somewhere not sure? NEED HELP! THANKS, Jason

Answer
Jason,

Just to remind you, my expertise lies in the older 356 models.  Luckily, many early designs/concepts have lasted since the early 50's and appear in revised forms on 911's, 914's 944's, Boxsters, etc.  Where this happens I'll promise to try to give you the best answer I can.

You didn't indicate whether you were talking about a 944, 928, or 911.  It shouldn't make a difference, but I only have a wiring diagram for the 944.  So I'll assume you've got a 944 for this answer.

Let's check the easiest possibility first.  If you lost a ground, here's a way to check for it.  Locate the fuel pump and the brown wire connected to it.  Disconnect the brown wire and use a continuity tester to check the now loose end oif the wire with a real ground, like back to the negative side of the battery.  You want the the reading to be zero.  That means there is conmtinuity and the brown wire is your good ground... and you can put it back together.

There's a fuse that you should check...my diagram indicates that fuse #34 powers the fual pump, and not a relay.  Check that out and see what you find.

I'm concerned we may be talking about different cars if you have two fuel pump relays and my documentation shows none.  Get back to me with your findings...we'll track down your problem.

Dave