dogholes

Hi,

lHi, I have an Audi 100 C3 2.3 5in-line which stalls briefly after the start. The problem started when the car stalled at 70km/h with a backfire and didn't run since. the timing belt was checked , the distributer and cap + rotor and wiring are exchanged, the whole fuel injection unit including fuel pressure regulator etc was replaced with a used one from a car that was running well before. All conections inside the engine room where checked und cleaned. The problem still exists..... What else could I check?
I would appreciate any tip!

latchkeykid

Sounds like either the distributor Hall Sensor or possibly bad ignition grounds. This is an 89 non-turbo?

ktownboostn

ISV possibly ?

dogholes

Hi,

thanks for your replies. I'll try the hall sensor tonight. I keep you posted.
What is the ISV ?? Do you talk about the computer or so called control unit?

Greets!

dogholes

Hi guys,

I tried a used distributor from a car that was supposly running before, but without success.
the car has pressure all over the fuel system, but almost no fuel arrives in the gas lines that lead to the valves out of the fuel distributor. The only valve that gets gas is the cold start valve (thats why it starts up first I guess).
I also cleaned the ISV by the way and I exchanged the fuel filter today.

I'll take the sledge hammer out soon!!

There must be somebody else who had the same problems already ???!....

I would appreciate any hint!

latchkeykid

I'm not all too familiar with your set-up but do you have a warm-up regulator? It's on the D-side of the block, two fuel lines running to the fuel distributor....that controls your cold start fuel pressure. You could also have a flaky fuel-pump relay, on the 5000's the relay has a pin-out going to the ignition system and if it fails you won't get any spark not to mention fuel pressure period.

dogholes

Hi Latchkeykid,

thanks a lot for your replies!!
To answer your questions I don't have the Turbo model, my Audi has a K-III Jetronic system and a NF engine. The line from the tank has 90 pounds pressure, I have a new gas-filter. The line out of the gas filter leads into the fuel distributor and another line goes out of the fuel distributor on the other side. The line out of the fuel distributor goes into the pressure regulator (mechanic one) and back into the fuel distributor (I guess that's how the system keeps constant pressure) The pressure regulator releases the rest pressure through a separate line to the gas tank. This separate line stays dry, no matter how long the pump is running. The 5 gas lines which are supposed to lead the gas to the cylinders stay also dry (I also jumped the pump already to make it run constantly and I still dont get any gas out of these five lines (sometimes one or two drops made it into the lines, but never enough to keep the car idling)
I also have a good spark on all cylinders the problem is that they stay dry like the sahara.
Maybe now you can understand the problem better......
I really hope you have a better idea than I had till now..

Best regards

latchkeykid

Is there any chance you've got the plumbing mixed up? LOL..Nah doubt it. This sounds like your differential pressure regulator, on the CIS-E-III systems used on the 5k this is mounted on the front of the fuel distributor (behind the headlight) with one electrical connector. You may just have a broken wire at that connector like this guy...

Google Image Result for http://www.quattro123.com/4000/VacuumLEaks/MVC-383F.JPG

dogholes

no sadly all the wires are still good. would have been too easy I guess.
Could it be related to the hall sensor even if I have sparks ??
Maybe the mechanical pressure regulator which is located a bit hidden besides the fuel distributor. My knock sensor doesn't look that healthy anymore neither (plastic is cracked..)
any other guess? I really want my Audi back!!!

latchkeykid

Nah it wouldnt be the knock sensor. It may be that mechanical pressure regulator you mentioned but I still think the differential pressure regulator is the most likely culprit. Have you tried another fuel pump relay yet? That relay sends signals to the various fuel injection electronics, the ignition as well as the fuel pump itself.

The differential pressure regulator is pictured at the very end of that thread I linked previously.