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stan_5150 · Joined: 01 Sep 2006 Posts: 31 Location: Minnesota

I've read a couple threads on here regarding the fuel pump vs. the fuel pump relay. I'm going to see if I'm getting power to the pump. After wiping away some grime I'm assuming that the orange wire is positive and the green/black is negative.....if I'm wrong I'm sure someone will let me know.

Anyhow, not being the mechanical type I'm wondering if anyone has any quick pics (or YouTube links) of the fuel pump relay and what needs to be done to understand the wiring in the bundles. As far as I know there hasn't been any modification to the wiring/electrical to the car. In fact, all the electrical seems to be working fine. Any suggestions are welcome. Thanks.

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1978 924 N/A

winddude · Joined: 15 Jan 2020 Posts: 61 Location: Vancouver Island

yea, green/blk would be positive, I think the orange wire should be brown...

!tom · Posted: Thu Aug 20, 2020 3:31 am Post subject:

I've discussed some of my findings about my fuel pump relay (also from a '78) in this thread.
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78 924 NA
5-lug

stan_5150 · Joined: 01 Sep 2006 Posts: 31 Location: Minnesota

stan_5150 · Joined: 01 Sep 2006 Posts: 31 Location: Minnesota

Ok an update on my troubleshooting attempts. Remember, not a mechanic here so if I get some terms wrong please don't be too harsh

I pulled the fuel pump relay and tested it tested 12.2 volts between 87 and 30. So I think that the relay itself is still serviceable.

I pulled the leads going into the fuel pump itself, and when engaging the starter it registered between 8.09 - 9.17 volts.

I'm leaning towards changing out the fuel pump. Am I missing anything in my rudimentary testing?

Any ideas or suggestions are welcome. Cheers.

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1978 924 N/A

Paul · Posted: Sun Aug 23, 2020 11:28 pm Post subject:

If the fuel pump runs when the relay is bypassed with a jumper and if the car runs fine, the fuel pump is not the issue.
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White 87 924S "Ghost"
Silver 98 986 3.6l 320 HP "Frank N Stein"
White 01 986 "Christine"
Polar Silver 02 996TT. "Turbo"
Owned and repaired 924s since 1977
Porsche: It's not driving, it's therapy.

stan_5150 · Joined: 01 Sep 2006 Posts: 31 Location: Minnesota

Paul · Posted: Mon Aug 24, 2020 3:27 am Post subject:

If you haven't already, pull the fuel pump relay and put a jumper between 30 and 87 and see if the pump runs. If not hit the pump with a rubber mallet a couple of times while the jumper is still in place. If the pump doesn't start remove the jumper before the pump overheats.

To further test the pump remove the wires and use an ohm meter between the terminals. If you get infinity the pump is shot.

https://www.harborfreight.com/7-function-digital-multimeter-63759.html
_________________
White 87 924S "Ghost"
Silver 98 986 3.6l 320 HP "Frank N Stein"
White 01 986 "Christine"
Polar Silver 02 996TT. "Turbo"
Owned and repaired 924s since 1977
Porsche: It's not driving, it's therapy.