Interesting failure mode.

I have a 200k+ mile 80q. Last few months, every now and again would not start on the first key turn, but sounded like it would "catch" on
one or two cylinders, then die. Second key turn would start it. This happened every so often, then the frequency picked up to almost every time the motor was started.
Then, one day, the second key turn didn't start it. Had it towed, and it started just fine for the mechanic. He went through it, and couldn't find any problem. Cleaned up some contacts, added dielectric grease in a few places, car ran well and started on first key turn.
For a week. Then the first key turn didn't do it, but the second did. Then another failure, and another tow. Car worked fine at mechanic's place. More replacement wire ends, diagonstic charges, car works fine as an extended loaner to the mechanic.
Get 200 miles from home. Car fails. Subsequent tow does NOT result in a successful start. Hooray! A failure to be diagnosed. Jumpering past the relay did not produce any fuel pump action. A dying fuel pump??? What a strange failure mode. All the other VAG fuel pump failures I've ever heard of are sudden, or give warning through noisiness. I have never experienced, nor heard of, a gradual failure like this.
As a car, this one has been very reliable, and quite kind to our bank account. It's even easy on gas when I remind myself to keep out of the throttle. :) $250 on a fuel pump is a little higher than I like, but I'll accept it if this one lasts for 200k miles.
E.P.
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EP, The failure mode may also be the ignition switch, for if there is no contact at the switch, the relay will not make the pump run even if it is jumpered. If you've already sprung for the fuel pump, keep the old one - it may still be good. Cheers! Steve Sears 1987 Audi 5kTQ 1980 Audi 5k 1962 and '64 Auto Union DKW Junior deLuxes (SPAM Blocker NOTE: Remove SHOES to reply)

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Steve Sears wrote:

contact
jumpered.
still
Well, as chance would have it, the switch was replaced two years ago because it failed. At nearly 200k miles, I'd say the original did a good job. :)
I thought of that too - I had told the mechanic to bypass every possible bad connection to test the pump. Direct connection to the battery did not run the pump.
Thanks for the advice, in any case!
E.P.
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The fuel pump relay might be getting bad and resulting in intermittent failure.
But, my first guess would be dirty injectors causing flooding. Try to hold the gas down about 1/3 when starting. This will tend to clear the flood and if it helps you probably have dirty injectors. Run 1 or 2 bottles of Techron injector cleaner.
Another possible issue is a bad fuel check valve used for maintaining pressure when the engine is off. This is probably located on the fuel pump but not sure on your car.
Tony '91 100q 5spd '98.5 A4 1.8TQ 5spd
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Tony wrote:

intermittent failure.
No. Jumpering around it did not cause the FP to run.

hold the

and if it

Techron injector

No. The injectors have been replaced recently.

pressure
not sure

No. Previous pressure tests have revealed this to not be the case. In any case, jumpering around the relay should cause a good pump to run.
E.P.
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Check ww.blau.com tech tip page. There was some discussion about starter motor causing similar problems.
Tony 96 S6

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Tony Curran wrote:

starter
I didn't find a specific page at either "www.blau.com" or "ww.blau.com".
Am I missing something?
E.P.
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Try: http://www.blauparts.com /
Top posting because I like it that way ...
TonyJ
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Tony wrote:

Thanks. The starter tip doesn't apply - the starter has never failed to turn the motor over. I can run the battery flat turning the motor. Just doesn't fire up.
The fuel pump seems to have cured it.

Well, you know my opinion on that... :)
E.P.
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