Classic Audi Technical Mech/Tech Engine » Audi 90 Quattro starting problem

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Old 19-11-17, 07:22 PM   #1
Ecosse
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Default Audi 90 Quattro starting problem

Hello !
I am a new member with two current Audi projects - a 1985 GT Coupe which is up and running and roadworthy and a bit of a sad 1988 90 Quattro.
I am hoping that I can get some advice - It is the 90 Quattro (a new acquisition) that is causing a bit of a headache - it will not start.
The fuel pump can be heard humming for a moment when the ignition is switched on and the engine will turn over and run for perhaps up to 3 seconds and then dies. I should add that I have been told the car has been stored for around 6+ years so it is a bit of an unknown quantity.
I am struggling to find layout diagrams for the wiring especially the auxiliary relays under the steering colum where someone seems to have removed some of the relays . I have identified the fuel pump relay on the auxiliary panel - labelled 76 but not sure what else should be there - one seems to have a jump wire plugged in. I was going to replace pump relay first .
Does anyone have a diagram / photo of the auxiliary relays ?
Any thoughts on the problem gratefully received thank you !
Cheers !
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Old 19-11-17, 07:39 PM   #2
John.
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Congratulations on your recent acquisition, it's fair to say no car likes sitting idle for a long time......is it a 2.2 KV engine? Are you thinking the pump is priming but the relay isn't staying switched when running?
Any more info on the car? ......any pictures?
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Old 19-11-17, 08:25 PM   #3
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Thanks - I am slowly piecing some history together - discovered it was sold at Brightwells over a year ago for a song and seems to have languished at a small dealer for the last year.
The papers I have seen so far ( still trying to get more out of the dealer ) show a substantial rebuild about 8 years ago including a 2.6 litre conversion plus 8 valve head gearbox and suspension work . It has done circa 155 k miles .
Photos to follow !
It does seem that the pump primes but for whatever reason may not continue running . Maybe it isn't the relay but an ignition / ecu problem ?
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Old 19-11-17, 08:36 PM   #4
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Well, if the correct engine is unknown, maybe we could have engine compartment photo of a good quality so that engine management type can be determined?
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Old 20-11-17, 12:34 PM   #5
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Quote:
Originally Posted by John. View Post
Congratulations on your recent acquisition, it's fair to say no car likes sitting idle for a long time......is it a 2.2 KV engine? Are you thinking the pump is priming but the relay isn't staying switched when running?
Any more info on the car? ......any pictures?
Run a seperate 12 volt supply to the pump (ok for testing as unused fuel will return to the tank) and try again if it runs its the relay at fault. Also on b3 coupes (OK this is a saloon) when they get old the pump wiring can fail when running under load I had to replace it on ours when it was around 12 years / 160k old to get it to run.
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Old 20-11-17, 01:00 PM   #6
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Sounds very interesting especially now you say it's had a 2.6 conversion.Looking forward to pics.
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Old 20-11-17, 01:44 PM   #7
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fuel pump relay should be in the main fuse box, not the aux panel.

relay 76 is normally the abs relay with a fuse on top
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Old 20-11-17, 02:56 PM   #8
Ecosse
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[IMG][/IMG][IMG][/IMG]

Here are two photos of the car - more to follow.
The engine work was undertaken by TSR Performance .
Re location of the fuel pump relay - none of the diagrams on the fuse box cover under the bonnet or on the panel below the steering column mention the fuel pump relay . Relay 76 may be the ABS but the relay diagrams don't seem to match the car !
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Old 20-11-17, 06:28 PM   #9
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pictures speak 1000 words sometimes.

Your fuse box cover may look something like this



FPR is number 10. I'll be honest though, I don't think that's related to your non start since you've already hinted that the pump primes when the ignition is first turned on - this suggests s working relay
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Last edited by mikes2; 20-11-17 at 06:45 PM.
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Old 20-11-17, 07:18 PM   #10
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If its not the pump it could be the ignition switch, I've seen a similar problem on a VW Polo where the car would turn over and start to fire then cut almost immediatly, twas the switch at fault. Was supplying power whilst cranking the engine but when turned back to running position it cut the power. It was hard to diagnose as when in the switched on position (prior to cranking) it was supplying power but after cranking position when back in the switched on position there was no power !

Last edited by quattrodave; 20-11-17 at 07:22 PM.
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