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.

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)
> wrote in message
oups.com...
> 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.
>

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


wrote:
> 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.
>

Tony wrote:
> The fuel pump relay might be getting bad and resulting in
intermittent failure.

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

> 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.

No. The injectors have been replaced recently.

> 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.

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.

Steve Sears wrote:
> 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!

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.

Check ww.blau.com tech tip page. There was some discussion about starter
motor causing similar problems.

Tony
96 S6

> wrote in message
oups.com...
>
> Tony wrote:
>> The fuel pump relay might be getting bad and resulting in
> intermittent failure.
>
> No. Jumpering around it did not cause the FP to run.
>
>> 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.
>
> No. The injectors have been replaced recently.
>
>> 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.
>
> 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.
>

Tony Curran wrote:
> Check ww.blau.com tech tip page. There was some discussion about
starter
> motor causing similar problems.

I didn't find a specific page at either "www.blau.com" or
"ww.blau.com".

Am I missing something?

E.P.

Try:
http://www.blauparts.com/

Top posting because I like it that way ...

TonyJ

wrote:
> Tony Curran wrote:
>
>>Check ww.blau.com tech tip page. There was some discussion about
>
> starter
>
>>motor causing similar problems.
>
>
> I didn't find a specific page at either "www.blau.com" or
> "ww.blau.com".
>
> Am I missing something?
>
> E.P.
>

Tony wrote:
> Try:
> http://www.blauparts.com/

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.

> Top posting because I like it that way ...

Well, you know my opinion on that...

E.P.