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Glen931 · Joined: 11 Mar 2005 Posts: 52 Location: Grants Pass, Oregon

While driving my 931 it acted like i had run out of fuel and i had just filled the tank. i couldnt hear the fuel pump when turning the key anymore so i checked the relay under the steering wheel. the fuse on the relay had a bad connection and was arking at each end. i was a hundred miles from home so i tried to get a good contact and limp it home. another 25 miles down the road it dies again with lots of burning electrical smell from the fuse. i had to get the car towed off the highway and to a mechanic. put a new fuse in it and tried it with no luck. so im pretty sure the relay is bad now. the car no longer gets fuel of course but it also doesnt get spark anymore.

Would a bad fuel pump relay have anything to do with loosing ignition spark or am i looking at multiple problems now?

I also noticed a 4 pin electric plug on the passenger side that was not connected to anything. it comes from below the exhaust manifold. all 4 pins are in line 3 close togather and one is away from the others. just wondering what that was.

I know i sound like an idiot but i havent seen or driven the car in a year and a half and now its stranded at an auto shop 70 miles from where i live. The people at the shop seem like good mechanics but they have never worked on a 924 or 931. any help is greatly appreciated.
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"Nitrous is like a hot chick with an STD, you know you want to hit it, but you are afraid of the consequences"

1980 porsche 931 beige
1987 Porsche 951 red, 51kmiles.. prefect cond.
1978 ford fairmont wagon 2.3 turbo engine

Smoothie · Posted: Thu May 17, 2007 11:50 am Post subject:

Glen931 · Joined: 11 Mar 2005 Posts: 52 Location: Grants Pass, Oregon

The fuse didnt burn out, it just got some arc burn on the ends. when the ignition is on i can fiddle with the fuel pump relay and it sounds as if the fuel pump is engaging if i hold it in place, but when i do this the relay heats up quite a bit and has been melted a little. There is no possibility of the mechainic being shady cause I was working on the car with him. As for that plug, I wasnt able to get under the car to see where exactly it went. the plug was clean on the inside which made me suspect that it was plugged in. thanks for the imput, it looks like im gona have to drive up there and try to figure it out.

EDIT: That plug is from a 4 wire O2 sensor that is not connected to anything and was not connected before the problem. It was just used to fill the hole in the exhaust.
_________________
"Nitrous is like a hot chick with an STD, you know you want to hit it, but you are afraid of the consequences"

1980 porsche 931 beige
1987 Porsche 951 red, 51kmiles.. prefect cond.
1978 ford fairmont wagon 2.3 turbo engine

Smoothie · Posted: Fri May 18, 2007 11:13 am Post subject:

I'd rig up a jumper wire with 1/4" male spade connectors at each end and an in-line fuse holder in the middle and bring a few spare 25A fuses for it. -And jumper 30-87 where the fp relay goes as a test before plugging in a shiney new fp relay.
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"..it's made in Germany. You know the Germans always make good stuff."

'82 924T, US version, dark green metallic, 5 speed Audi 016G gearbox

924RACR · Posted: Fri May 18, 2007 9:50 pm Post subject:

Sure, what Smoothie said - I had this problem with the fuse on my DD '82 heating up badly, enough to burn flesh. Turns out it was, apparently, excess resistance caused by corrosion on the terminals in the fuseblock.

Fix was to cut the wires off the fuseblock (IIRC #2 on the aux fuse block) and run them through two seperate brand-new inline fuse holders. Never had a problem since.

IMO, the 931 suffers from lousy electrical design. It was just a clapped-out 924NA system, designed for the early cars that had no ECUs, power accessories, AC, etc. When they added on all the modern conveniences, they neglected to upgrade the electrical system properly, so incurred the resultant durability hit. Not that horrendous given that it's 20-25 years later, but still disappointing.

Really the 931 should have had the electrical system that went into the 944... much more capable/robust.
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Vaughan Scott
Webmeister
'79 924 #77 SCCA H Prod racecar
'82 931 Plat. Silver
#25 Hidari Firefly P2 sports prototype

Glen931 · Joined: 11 Mar 2005 Posts: 52 Location: Grants Pass, Oregon

New feul pump relay fixed the fuel problem as well as the spark problem.

Thanks for the help everyone
_________________
"Nitrous is like a hot chick with an STD, you know you want to hit it, but you are afraid of the consequences"

1980 porsche 931 beige
1987 Porsche 951 red, 51kmiles.. prefect cond.
1978 ford fairmont wagon 2.3 turbo engine