My car is a 2003 Audi A6 Quattro 3.0L (engine code AVK). 134,XXX miles.

I was sitting at a red light 2 days ago when my car suddenly stopped running. It behaved like it had just run out of gas (as opposed to an electrical shutdown). I had no indication prior to this of a problem - the car had been running very well for quite some time. I cranked and cranked, but only occassionally did I get any kind of combustion. I had a cheap OBDI II reader with me, so I read the codes: P0741, P0421 and P0431. The latter two are with the cat converters, and I've had those for a while. I had not seen the P0741 before. It appears to be with the torque convertor (everyone I've asked says that it is probably not causing the engine to not start). I continued cranking while I waited for the tow truck.

I eventually had it towed home. I checked the codes again, and now a 4th code was set: P0321 (best indicators are that it is with the engine speed sensor, which may or may not be the same as a crank shaft position sensor). After letting it set for 8 hours, I tried to start it. The first crank gave a little combustion for about 2 seconds, and then after that, pretty much no combustion. So it has gone the last 2 days. I can occassionally get some combustion, but it is extremely short lived. The first try after letting it sit seems to give a little combustion, never more than a second or two.

I don't have a VAG-COM, but here's what I've tried.

I removed the top timing belt covers and inspected the timing belt. It appears to be completly tight. However, I can't tell if it is still in time.

I removed the big air intake hose. I had someone turn the engine over while I sprayed GumOut towards the air intake. I was able to keep the engine running as I long as kept shooting puffs of GumOut at it. A few seconds after I stopped, the engine died. I think this means that I am getting spark and that the camshaft and crankshaft sensors, the spark plugs, ignition coils and timing are OK. It seems I am dealing with a fuel delivery problem.

I replaced the fuel pump relay with one from an A6 2.8L engine (same part). No difference.

I loosened the banjo bolt on the fuel filter a tiny bit (on the engine side of the filter). Gasoline dripped out. I had someone turn the ignition key very briefly to the on position (not start). Gas sprayed out severely. This leads me to believe that the fuel pump works and the fuel filter is not clogged. However, I don't know if it is delivering the correct pressure or not.

I removed the vacuum hose from the Fuel Pressure Regulator (FPR) and turned the ignition on and waited. No fuel leaked out the FPR. I removed the FPR completely. Gasoline dripped out the FPR seat, probably at least 1 a teaspoon amount. I waited an hour for the gasoline to dry, then I turned the ignition on. No fuel came out - I THINK THIS IS A CLUE. I think fuel should have come out of this pretty strongly. As far as I can tell, there is no place to measure the fuel pressure at the fuel injection rail on this car.

Any recommendations?

Thank you in advance.