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GDK · Joined: 22 Jan 2004 Posts: 11 Location: Oregon, Medford

I need your help guys...
I am intending to enter my first auto-x this weekend and my fuel pump isn't getting any power. I changed my fuel pump relay and no help. Also, I have no power to the aux air valve or the worm up valve. I have jumpered the fuel pump at the relay and it does run.
Do any of you know where I might look to find a problem area common with all of these components..

Thanks in advance
GDK

P.S. The fuse is good
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1981 931
1987 XJS V-12

Paul · Posted: Wed May 11, 2005 2:09 pm Post subject:

Make sure your over boost switch is plugged in.
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White 87 924S "Ghost"
Silver 98 986 3.6l 320 HP "Frank N Stein"
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Owned and repaired 924s since 1977
Porsche: It's not driving, it's therapy.

924guy · Posted: Wed May 11, 2005 10:13 pm Post subject:

just some thoughts,
did you check to see if your getting power to the relay sockets? you should have at least two power sources at the relay (i forget which slots they are) one is the main power, one is the relay trip from the ignition, and the rest are ground and output to the f/p. its possible a direct connection connection on the rear of the fuse panel has worked itself loose, id also check the connection at the ignition switch , just to be safe, theres an energiser circuit there that tells the relay to run . if all of those test "good" then the problem could be between the relay output, and the fp itself. you can run a temporary jumper wire to the f/p 's to see if they kick on directly.
find out how to run it, and work between known "good" circuits and you ll figure it out.. the overboost switch is a very suggestion as well, if its not pluged in, she wont run, thats its job..cut out the fp circuit to prevent o/b damage to the engine..
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Eric
78 924
82 931 SE "smokey"
99' VehiCross
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GDK · Joined: 22 Jan 2004 Posts: 11 Location: Oregon, Medford

Thanks guys for the input

I jumpered the pump at the relay panel, L13 and L15 I think, so I will assume that the connections at the rear of the panel and to the pump are ok. Also there is power to the coil with the ignition on.
The overboost switch is plugged in but may have failed. Does this provide ground for the entire circuit? I will test continuity between the switch and ground, there should be 0 to low Ohms. If the switch has failed I will ground the wire and make see if the pump runs at this point. If it doesn't I will return for more advice. If it does, I will r&r the switch and head for the track.

Thanks again
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1981 931
1987 XJS V-12

GDK · Joined: 22 Jan 2004 Posts: 11 Location: Oregon, Medford

So here is the latest if anyone is interested...

I appears that there is adequate voltage at the proper terminals of the relay but ther isn't enough available amps to close the relay...not sure how I'll fix it, any suggestions?
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1981 931
1987 XJS V-12

Smoothie · Posted: Fri May 13, 2005 6:08 am Post subject:

I've seen that (volts ok, but not enough current) when grounds are bad. -But it could also be poor conduction through a connector somewhere and personally, I've had problems with the connectors on the back of the fuse-relay board. You could pull the connectors one at a time and look for burnt or discolored pins. -Or first identify which pins are involved specifically with the fuel pump and relay, then go straight to whatever connectors are involved and pull them. The connectors are labeled A - F as shown in the 76-82 Haynes pg.237 and pins are identified by connector letter and a number like "C12", "F5", etc. Sometimes, all that's needed is to unplug-replug a connector to "clean" it so even if you don't find burnt pins, the problem might be resolved by just the unplug-replug.
As far as grounds... there's a ring of them hidden up beyond the fuse-relay board, one in the luggage area between the taillights, one at each frame rail behind each headlight, one at the ignition coil, obviously one from the battery, etc. Those are the main ones. I'd suspect the one hidden up under the dash and the one at the coil first, but they probably all could use a cleaning by now.
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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

GDK · Joined: 22 Jan 2004 Posts: 11 Location: Oregon, Medford

Smoothie

I came across an old post of yours from Nov. 9 2004 that said much the same thing. The individual who was having the problem had success with the solution.
It appears to be quite a job getting to the connectors and keeping them straight ( if it gets hosed up the car is close to garbage ), but it wont be the hardest thing I've ever done.

Well here goes, I'll let you know.

BTW I have a dog/wolf, that looks very much like yours but doesn't dress as well...
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1981 931
1987 XJS V-12