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Fuel pump issue, no power to pump
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winddude  



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

PostPosted: Sat Mar 21, 2020 6:21 am    Post subject: Fuel pump issue, no power to pump Reply with quote

Trying to diagnose my no fuel issue in my 1980 NA 924. Both external and internal pump run if I power them directly. About a month ago I had no issues starting the car, nothing has been modified or changed.

I've tried jumping 30 and 87 on the relay, still not getting power at the pumps. The fuse is good. What other steps can I try?

The car is relatively new to me, there appears to be two additional relays separate from the OEm realy panel one appears to be for the stereo, has a VW relay in it, the other no idea, but it's similar to Fuel pump realy, but has no relay in it.

Any other ideas for diagnosing?
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Paul  



Joined: 02 Nov 2002
Posts: 9491
Location: Southeast Wisconsin

PostPosted: Sat Mar 21, 2020 8:15 am    Post subject: Reply with quote

Check for 12 v (with a test light) at 30.

Check for continuity from 87 to the pumps.
_________________
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.
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!tom  



Joined: 28 Aug 2006
Posts: 1930
Location: Victoria, BC Canada

PostPosted: Sat Mar 21, 2020 8:20 am    Post subject: Reply with quote

Even though the fuse is good, sometimes you can get a bad connection.

Is it possible the contacts in the relay socket have degraded and are no longer making contact?
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winddude  



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

PostPosted: Sat Mar 21, 2020 9:02 am    Post subject: Reply with quote

!tom wrote:
Even though the fuse is good, sometimes you can get a bad connection.

Is it possible the contacts in the relay socket have degraded and are no longer making contact?


You where right with your first thought, the fuse (#2) is getting a really bad connection, even cleaning the terminals ( with alcohol, I feel kinda bad ) doesn't help, I have to wedge them together. So looks like I'll need to look at replacing the fuse holder.

Any suggestions? I'm hoping I can use a 15a blade fuse, or open to fixing the euro style terminals, ideas?

If some one can confirm, there should only be the two terminal connections to the fuel pump fuse black/green & red/white off of 1 terminal and red/black off the other end? I also had a red/black and green/black off the two side terminals, but they look they are a little newer and going into an after market harness.


Last edited by winddude on Sat Mar 21, 2020 9:08 am; edited 2 times in total
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Paul  



Joined: 02 Nov 2002
Posts: 9491
Location: Southeast Wisconsin

PostPosted: Sat Mar 21, 2020 9:06 am    Post subject: Reply with quote

If you have 12v at 30 and continuity from 87 to the pumps, they will run when 30 and 87 are jumped.
_________________
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.
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winddude  



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

PostPosted: Sat Mar 21, 2020 9:10 am    Post subject: Reply with quote

Paul wrote:
If you have 12v at 30 and continuity from 87 to the pumps, they will run when 30 and 87 are jumped.


Yes, I've now narrowed it down to an issues with the fuel pump fuse terminals. Tried cleaning them, but I seem to have to wedge them against the fuse to get continuity. Ideas?
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Paul  



Joined: 02 Nov 2002
Posts: 9491
Location: Southeast Wisconsin

PostPosted: Sat Mar 21, 2020 9:14 am    Post subject: Reply with quote

87 to fuse re/bk
fuse to pumps bk/gn via T1a connector near fuse/relay board
_________________
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.
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Paul  



Joined: 02 Nov 2002
Posts: 9491
Location: Southeast Wisconsin

PostPosted: Sat Mar 21, 2020 9:16 am    Post subject: Reply with quote

Can you squeeze the terminals closer together?

Can you move the circuit to an empty space on the fuse holder?
_________________
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.
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winddude  



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

PostPosted: Sat Mar 21, 2020 9:22 am    Post subject: Reply with quote

winddude wrote:
If some one can confirm, there should only be the two terminal connections to the fuel pump fuse black/green & red/white off of 1 terminal and red/black off the other end? I also had a red/black and green/black off the two side terminals, but they look they are a little newer and going into an after market harness.


These are on the flow diagram for the turbo, but they just go off the page. :s, my car is not turbo. Maybe the harness was changed at some point.
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Paul  



Joined: 02 Nov 2002
Posts: 9491
Location: Southeast Wisconsin

PostPosted: Sat Mar 21, 2020 9:23 am    Post subject: Reply with quote

Fuse 2 should be 25 amps, it also powers the WUR and SAV.
_________________
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.
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winddude  



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

PostPosted: Sat Mar 21, 2020 9:23 am    Post subject: Reply with quote

Paul wrote:
Can you squeeze the terminals closer together?

Can you move the circuit to an empty space on the fuse holder?


I tried squeezing them the don't seem to stay, the metal prongs seem to fatigued. I'll try moving them never know might help.
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Paul  



Joined: 02 Nov 2002
Posts: 9491
Location: Southeast Wisconsin

PostPosted: Sat Mar 21, 2020 9:29 am    Post subject: Reply with quote

You could also bypass it with an external fuse holder. I would use a modern blade type holder.
_________________
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.
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winddude  



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

PostPosted: Sat Mar 21, 2020 9:53 am    Post subject: Reply with quote

Paul wrote:
Fuse 2 should be 25 amps, it also powers the WUR and SAV.


You're right should be 25a, there was a 16a in, maybe that's part of my issue.
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winddude  



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

PostPosted: Sat Mar 21, 2020 10:00 am    Post subject: Reply with quote

Paul wrote:
Fuse 2 should be 25 amps, it also powers the WUR and SAV.


25a solved it!

Do you know what color the WUR and SAV wires are? Also looking at haynes their in the flow diagram for the turbo model but not the NA :s I'm assuming that was what I unplugged. ed/black and green/black going into a harness that has just 3 wires, third is red and wasn't connected to anything :s
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Paul  



Joined: 02 Nov 2002
Posts: 9491
Location: Southeast Wisconsin

PostPosted: Sat Mar 21, 2020 10:08 am    Post subject: Reply with quote

Page 263 of the Haynes shows the wiring
_________________
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.
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View user's profile Send private message Send e-mail
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