S4 Starting but won't idle/run

[tuntsfaah]

I have a problem that had developed over the past weekend. After filling my tank at Citgo, I started and stopped at a store. When I got back to the car, it wouldn't run. It would start and idle for a second or two and then die.

We, my wife and I, thought it was the gas, so we siphoned 3gals out of the tank and added Lucas Octane Boost. Then we jumped the clutch and it started, we went all over the placed stopped here and there and it was kewl.

However, this morning we went out and the same system reoccurred...jumped the clutch, restarted it and it worked. On my way back to the house, I was cruising along my route when all of a sudden I lost power and the engine started dying out! My effective solution did not work on the car anymore.

I got some help and while they were tapping the gas tank the car would start and even idle, but when the tapping stopped, the car would die a min or 2 after. I could even do high revs, but when I put it in first to move off it dies.

Could this be that my fuel pump is going or/and my fuel filter is clogged? Has anyone had this issue before...Audi/VW?

[mysteryman047]

I have a POS taurus im actually in for work right now and it was doing the same thing. cleaned the fuel filter and no problems today so far.

[tuntsfaah]

I have a POS taurus im actually in for work right now and it was doing the same thing. cleaned the fuel filter and no problems today so far.

Thanks...I will try cleaning/replacing filter to see if that works. Hopefully that's the issue!

BTW...I have never cleaned a filter, is there a DIY thread?

[NefMoto]

Check for error codes using VAG-COM. You may have a large boost leak, you could try disconnecting the MAF and see if the car runs, or do a pressure test.

[megafreakindeth]

fuel pump

[tuntsfaah]

Check for error codes using VAG-COM. You may have a large boost leak, you could try disconnecting the MAF and see if the car runs, or do a pressure test.

How would a boost leak just develop all of a sudden like that?
I doubt it was one though, the car would be able to start and idle without shutting off. Boost leak will allow the car to run in limp mode, but in this case the car won't even stay on, hence not a boost leak.
I didn't get any check engine lights and still don't have one.

[NefMoto]

If your TBB pops off, or you have some other sort of massive boost leak after the MAF, the car will not run more than a very lumpy idle.

Disconnecting the MAF sensor and seeing if that helps the problem is one of the easiest things you can try.

[DaveS4]

Yeah, unplug the MAF. There's a good guide somewhere around here showing you how to diagnose the issues if the MAF makes an issue, maybe somebody could post that?

[coreyj]

does sound like a bad or clogged fuel pump/ filter

[NefMoto]

If you want to check the fuel system, buy a remote fuel pressure gauge and T into the fuel supply line in the engine bay. Then check fuel pressure at idle and while driving, and compare against boost pressure.

[tuntsfaah]

OK so I found out it was the fuel pump. But I don't have the time or equipment to do a replacement.
I took it to my mechanic and they said in order to switch the pump I need to get the pump with assembly. I was told the lines were crimped and cannot be salvaged when installing the new pump.

Has anyone who changed their S4 fuel pump had to do this? Any picture or video tutorials on this for the B5 S4?

Need info asap...car is in shop and scheduled for repairs tomoro