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Jazzerpet · Joined: 07 Apr 2003 Posts: 186 Location: Omaha, NE.

I recently changed to the five lug system on my 931. After making the e-brake connection I pinched the factory alarm wire between the seatbelt bolt and the body, thus grounding it. I didn’t notice the problem until I got home, about a 15-minute drive. After I shut the car off it would not start and stay running. A short trip through what I recently done reveled the grounded wires.

After I corrected the problem the car started up and ran fine. I took it for a drive and it died on me. The battery was completely dead. I rolled down a hill and popped the clutch, started up again. When I got home, shut it off, restarted without a problem. I noticed the pump ran for a wile after shut down.

Today I took it in for tires, when I got to the store the pump would not shut off at all. I had to disconnect the battery. The car runs fine but with it off and keys in hand the pump runs on. I hear both the pump and frequency valve running. This problem is somewhat intermittent as the pump ran only for a few seconds when got back home.

Finally to the question, what would make this happen? Related to the pinched wire?

Jim
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1980 931
1985 ½ 944
Member of the “Omaha Crew”

Lizard · Posted: Tue May 24, 2005 11:16 am Post subject:

somehow the ign is still producing a signal, as the fuel pump needs a signal to stay running, it is also possible that the ign switch is partially defective
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3 928s,

Paul · Posted: Tue May 24, 2005 11:49 am Post subject:

Does your car still have the stock fuel pump relay in place?

Have you made any changes to the stock wiring?

Jazzerpet · Joined: 07 Apr 2003 Posts: 186 Location: Omaha, NE.

It could be the switch. I have a spare I could swap out.

I changed the wiring harness a few months ago. Have a few bugs to work out. The biggest is the oil, break, and parking break light is on, unless I press the break pedal. The fuel relay is still in place, the harness is stock, no modifications.
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1980 931
1985 ½ 944
Member of the “Omaha Crew”

CMXXXI · Joined: 05 Nov 2002 Posts: 1939 Location: Vicksburg, MS

My first inclination is a bad fuel pump relay. If when the pump "runs on", reach up and "rap" the relay with something and see if it shuts off. It's possible/probable that one of the contacts inside it is sticking. Swap the thing out if you have a spare and see if that cures the issue.
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'79 Eurospec 931

Paul · Posted: Wed May 25, 2005 6:22 am Post subject:

The relay should not be powered unless the ignition switch is in the run or start positions.

Edited to state that I was wrong about this, see post below....

Jazzerpet · Joined: 07 Apr 2003 Posts: 186 Location: Omaha, NE.

So in reality everything points to the ignition switch?

Work has me busy so I haven’t checked it yet.
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1980 931
1985 ½ 944
Member of the “Omaha Crew”

Paul · Posted: Wed May 25, 2005 11:09 am Post subject:

Something else is messed up since the car's ignition is shutting off when you turn the ignition switch to off.

I just checked the electrical diagram to make sure my memory was correct, and it's not!

The fuel pump relay is connected directly to the battery, so it is most likely your problem.
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White 87 924S "Ghost"
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Owned and repaired 924s since 1977
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