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

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Old 21-11-17, 04:56 PM   #11
Ecosse
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Thanks for the photo of the fuse box top and the advice regarding the ignition switch !
My under bonnet fuse box lid reads slightly differently - sorry about the quality of the photo but relay 10 on mine reads " Relay for manifold pre heater K - Jetronic " and there is no reference to the fuel pump relay on this lid - so Audi appear to have altered the positions of relays year by year ?
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Old 21-11-17, 05:31 PM   #12
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Highly unlikely, as that would had required major loom modifications, something only hobbyist would bother to do, not manufacturer. Relay socket 10 in C3 fusebox, used by C3, late B2, B3, B4, has been designed to have fuel pump relay, with additional consumers [with EFI present fuel pump relay also powers injectors and some other things] or not.
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Old 27-11-17, 01:23 PM   #13
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Well - it has now shifted from a starting problem to a running problem ! I replaced the fuel pump relay ( yes in the scuttle fuse box thank you ! ) and also topped up with some fresh petrol and injector cleaner on the basis that it had probably been standing 4+ years. After much winding on the starter it gradually coughed into life but now doesn't idle - runs at 2000 rpm +. Now when warm it will run for perhaps 3 or 4 minutes before gradually dying. Sounds good though ! It has obviously had an idle valve issue as a spare was lying in the front footwell ! So - next on the list is a clean of the valve and a hunt around for air leaks. Also intend to replace ignition components ( distributor cap / leads etc ) as all seem a bit ancient !
The engine gets quite hot as I had it running in bursts for maybe 15 minutes but neither the temperature gauge moves nor the fan comes on so maybe a fault with sensors as well ?
Onward and upward !
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Old 27-11-17, 04:08 PM   #14
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Sounds like it just wants a damn good service, then,...... sort out the sender issues possible air leaks and the isv and you could be revving to go.
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Old 24-12-17, 02:20 PM   #15
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An update - and unfortunatly not a lot of success ! Still basically a non starter .
I have replaced the fuel pump relay / cleaned the idle valve / dried out the air filter / replaced the idle valve relay / checked for air leaks / new coil + distributor cap + ignition leads + rotor arm / new water temp sensors on the front of the engine / checked wiring to the various sensors / replaced the thermostat - sticking I think / added fuel cleaner additive to the tank
And still it won't run properly !
The fuel pump runs ( it looks like a new pump under the rear of the car ) and after quite a few churns it will struggle into life for maybe a minute or so ( but won't idle ) and then dies misfiring . It won't restart at all for a few minutes and occasionally spits back and runs on when trying.
So where to now ? The car was laid up for quite some time - ( years ) so maybe fuel starvation ? Has the fuel filter clogged ( next on the list ) or the metering head pipe work clogged up ? I think there is a filter in the metering head as
well ?
Plugs out after a minute or 2 running - plugs not too sooty or wet - so doesn't seem to be over fuelling.
I have read that it is possible to check fuel flow by disconnecting one of the metering head pipes so that may be on the list to check.
Any further thoughts would be welcomed !
Thank you and Happy Christmas !
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Old 24-12-17, 02:57 PM   #16
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It's probably also worth checking the ignition timing and the injectors.
Just a thought​.

Good luck with it.
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Old 01-01-18, 12:22 PM   #17
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D82490DC-6D18-44D5-BA3D-BC04F023914C.jpeg

Well - finally some success !
Tried to remove the fuel filter but the filter connections were quite stubborn and lying on my back in the rain under the rear of the car wasn't very attractive so I turned my attention to the Bosch fuel distributor and removed the inlet banjo .
The result is shown in the photo - the filter was in poor shape being clogged with deposits . Took a bit of effort to get the filter out with a self tapper .
Result - the car now runs allbeit a bit rough but I guess it hasnt run for 4+ years and is going to take a bit of fettling.
Now looking at the cooling system - the dashboard gauge doesnt shift although
the engine gets hot - anyone know which sensor on the engine is connected to the temp gauge ?
Happy New Year !
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Old 01-01-18, 01:32 PM   #18
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The sender unit on the engine is likely to be a single terminal type........shorting the wire to earth to see if the gauge goes up would tell you that the wiring and gauge are ok, so suspect the sender.
A friend of mine had an issue with temp and fuel gauges on a B4 coupe and it turned out to be a connection on the PCB on the dash clocks....an easy fix apparently.

At least it's running now
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Old 01-01-18, 02:58 PM   #19
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Belated welcome & good find on the inlet banjo ,was going to suggest this (honest ) after I had trouble with this on mine -
http://www.classic-audi.co.uk/forum/...t=24419&page=2

Any pics of the car ?
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Old 01-01-18, 03:16 PM   #20
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Things like this are usually down to just a thorough service, glad your getting there and i'm sure it won't be long before it's all running tickety boo.
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