924Board.org

juno · Posted: Tue Aug 17, 2004 5:07 pm Post subject: Second fuse from back

Keeps melting or blowing. The one on the board that faces down. it's 8A. Is this a sign of a bigger problem?
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1980 924 Turbo RHD. 3" > 2.5" Stainless straight-through exhaust.

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

The circuits the fuses protect are listed by Peter_in_AU in this thread <click>. The second one from one end is the fuel pump fuse, so, yes it could indicate one or both of the pumps is/are drawing more amperage than it/they should and be an indicator of impending failure. It is possible that the in-tank pump's filter screen is clogged, causing the primary to work harder. By chance has anything been "hacked into" that circuit that might add an additional load to it?
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'79 Eurospec 931

juno · Posted: Fri Aug 20, 2004 9:01 pm Post subject:

Not as far as I know. One of the pumps does seem noisier sometimes. Looks like I best start to look for a replacement.
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1980 924 Turbo RHD. 3" > 2.5" Stainless straight-through exhaust.

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

Umm, the "8A" in your original post didn't hit home... can someone check me on this, but I think cars with dual fuel pumps should have a 16A fuse in the circuit. I don't have that info handy right now to confirm what it is supposed to be. Even if 8A is correct, a fuel pump is pretty pricy, it will pay to do some diagnostics before just running out and buying a replacement.
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'79 Eurospec 931

Smoothie · Posted: Sat Aug 21, 2004 4:20 am Post subject:

The 2 fuel pump arrangement uses a 16A fuse and the older single pump setup uses a 12A fuse.
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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

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

Now, send the cost of that replacement fuel pump to either one of us, and Smoothie and I will split it as our technical advisory fee.

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'79 Eurospec 931

juno · Posted: Thu Aug 26, 2004 1:58 am Post subject:

On the way home last night, one of the relays was clicking alot. Eventually, the car died and would not start again 2 miles from my house.

Haven't done any testing yet as it's been raining all the time.

I don't quite understand the test in the Haynes manual - is there another fuse actually inside the relay? It talks about refitting the relay with an 8A fuse. The relay doesn't seem to want to come off the board when I tried last night.
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1980 924 Turbo RHD. 3" > 2.5" Stainless straight-through exhaust.

marky522 · Joined: 02 Nov 2002 Posts: 335 Location: Port Huron, MI

if the fuel pump is the same as the na i have an almost new pump sitting in the shed if your interested make me an offer.

MArk

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

I'm guessing that you are guessing it's the fuel pump relay that was clicking? I've been one of the lucky ones who has never had a problem with the fuel pump circuit (knock on wood). But, I understand that sometimes the relay will get hot and quit working, and once it cools, it functions again. Did the car re-start hours later? You can always (temporarily) bypass the relay by jumpering it. With the jumper in place, the pump should run continuously, but I wouldn't leave it in place as a permanent "fix". It could be the fuel pump on the way out after all.

As I mentioned earlier, the pumps are pretty expensive, so it will be to your benefit to do some serious troubleshooting before deeming it the culprit and replacing it.

Some of the relays are terribly hard to get out of their sockets. I've gone as far as disconnecting the battery and using a thin screwdriver to pry the thing out. The sockets themselves are "clipped" onto the top of the fuse box, they slide in from behind and lock in place by a plastic tab.
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'79 Eurospec 931

Smoothie · Posted: Thu Aug 26, 2004 3:17 am Post subject:

The relays that have fuses in them have the fuse mounted on top and in sight with the relay plugged in. Apparently your relay doesn't have a fuse. Relays can be tough to remove - just keep rocking it back and forth while pulling. Once you get it out, with any luck you should see 16A stamped on it somewhere - if it says 12A, that could be part of the problem. If it doesn't show an Amp rating, post the part number.
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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

juno · Posted: Thu Aug 26, 2004 5:29 am Post subject:

Got it out eventually. It doesn't show an amp rating, but it is a KAE 3.300.300.

I forgot to mention the fan relay was very hot when it cut out, but temperature was fine. The rear screen heater fuse had also blown at some point - can't remember when i last used it but it worked then.

The car still won't start after being left for 24 hours. I'll do some testing as described in the haynes and see what i find.
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1980 924 Turbo RHD. 3" > 2.5" Stainless straight-through exhaust.

Smoothie · Posted: Thu Aug 26, 2004 5:46 am Post subject:

Ok - I was hoping to use the part number to tell what the amp rating was, but I don't recognise that part number.
Still can't say which is the problem - could be fuel pump (did you happen to check it to see if felt hot?) - could also just be a relay problem and since it's not a bad idea to have a spare fuel pump relay anyway, I'd pick up a new one and try it, but first try jumpering the relay to see if the pump's working and if it's getting hot (warm is ok, hot's not). If the pump runs warm or cool and the car runs with the relay jumpered, then plug in a new 16A 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

juno · Posted: Fri Aug 27, 2004 11:13 pm Post subject:

The pump ran with the relay jumpered. Fitted a new relay but the car still will not start. When it's jumpered the pump runs with the ignition off, right?
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1980 924 Turbo RHD. 3" > 2.5" Stainless straight-through exhaust.

Smoothie · Posted: Sat Aug 28, 2004 2:25 am Post subject:

So the pump runs with the relay jumpered, but did you try to start it then? Does the car run with the relay jumpered?
The relay needs a signal from the ignition to activate and provide power for the fuel pumps, so your problem could be with the ignition. Have you checked for spark?
If the car runs with the relay jumpered, but doesn't run with the relay installed, then obviously your pump and ignition are functioning, but there might just be a problem with the wiring from ignition to relay keeping the signal from getting there. In this case start by checking the connections at the coil.

I believe you need to have the ignition switched on for power to get to the fuel pumps when the relay is jumpered.
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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

juno · Posted: Wed Sep 01, 2004 10:26 pm Post subject:

The car seems to run fine with the relay jumpered. I only ran it for 3-4 minutes though. When it's jumpered, the fuel pump is on all the time even with the key out.
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1980 924 Turbo RHD. 3" > 2.5" Stainless straight-through exhaust.