[s-cars] Need Help - Won't Stay Running

[Tom Feller]

Help!

 

I have an odd problem.  My 92 S4 sometimes will not stay running after
starting. It will start fine but after about 10 to 15 seconds, it appears
the fuel pump shuts off and the car dies. It can be restarted but each time
it runs for a shorter period until it will not run at all. Most of the time
after 6 to 10 tries it starts up and runs fine. 

 

Since the problem started about 3 months ago, this has happen 4 or 5 times,
each time it eventually started and ran with out a problem. I have checked
it with my Prodiag after the events but it has not shown any faults. Again
after is starts it runs fine.

 

The last two days we have had some quite cold weather here in Portland, 15 -
20 degF. Sunday night the car would not start at all so I had it towed to my
friends shop on Monday. Sure enough, it would not start for him. He put a
fuel pressure gauge and confirmed that the fuel pressure starts to fall and
then car dies, leading to the idea that we are losing fuel rather than
ignition or injector trigger signals. Of course, after the car warms up in
his shop it runs starts and runs fine. He is an Audi expert with almost 30
years experience and has seen a lot of strange things but this one is new. 

 

Here is the most interesting point of the story. Whenever it will not start
the System Diagnostic display, you know with the bulb check and stuff, goes
crazy showing low fuel, bad brake lights, etc AND the front parking lights
come on! Dim but they are on. Once the problem goes away so does the problem
with the display and the parking lights.

 

So it sound like a ground problem and the whatever is bad is finding a
ground path though the parking lights. But how can the parking lights be
related the engine electronics? This problem did start after I replaced the
cam belt drive gear. Since I had to pull the front end off and swing the
radiator out is it possible I left a ground loose or pulled a ground wire
off? I don't remember anything like that when I did the job but who knows.
Well, I hope someone on the list does!

 

Thanks, Sorry about the long post.

 

Tom Feller