MrQuA4ttro

So I had an unfortunate mishap over this labor day weekend, and hope someone can give me some pointers before I have to resort to the "stealership".

Last Friday I had taken my A4 1.8TQ to the gas station, filled the gas tank and got a car wash. The car sat in my garage all saturday and sunday. Monday morning I woke up early to hit the golf course with a friend. Within 5 minutes into the drive the car started to "buck". Nothing like the hesitation you get or the misfire symptoms of a failed coilpack. Eventually the car stalled at a stoplight. I attempted to start it again, and it will idle for about 3 seconds @ about 300rmp before it stalls again. I disconnected and reconnected the MAF--no change. The car doesnt give me a CEL either, which I find kinda strange. When I attempt to start the engine, as soon as I push on the accelerator to give it gas, it stalls. I have no indications of leaks of any kind.

No changes made under the hood....just a full tank of gas. Thought I could have gotten some bad gas??

I hope someone can give me some insight...the wifey is threatening to sell the car! HEELLP!!

javanator

consider siphoning some out into a clear container of some kind that has a screw on cap (liter pop bottle, etc). You should be able to pick up clear vinyl tubing at a hardware store -- get like 5~6 feet of it so you don't end up tasting your gas. Just prior to siphoning, push the back of the car up and down to shake the gas in the tank up a bit -- bad gas usually has sediment in it which usually settles at the bottom of the tank. If you have bad gas, it's usually pretty evident when you look at it.

If the gas is bad, and you suspect the station where you filled up at, call the state agency for your state that regulates gas stations ASAP so they can get an inspector out to that station. If the inspector confirms they have bad gas, it gives you the case for the station to pay for flushing/cleaning your fuel system and any damages occurred.

Other possibility is failed fuel pump causing no fuel pressure. If you turn the ignition to start without cranking the car you should hear the pump for a few seconds pressurizing the system. If you don't, pull your fuse panel cover and check the fuse for the fuel pump -- panel will tell you number/location of the fuse for the fuel pump....20 amp fuse I believe. If you suspect fuel pump is bad, I think the Bentley has a trouble shooting procedure involving use of a multimeter that you can follow to verify the pump is bad.

quattrothatcould

If a little water got in the tank, that would cause those problems. Either pump the gas out or maybe try an octane booster if you think its solely bad gas...

MrQuA4ttro

Correct me if I am having the wrong train of thought here....but if the fuel pump had gone bad, I would have a loss of pressure in the fuel system...and should cause a CEL. Loss of pressure could translate to a leak for all the ECU knows? Does this seem logical?? I dont have a CEL at all...I need to siphone my gas and see what it looks like. According to the Colorado Oil & Gas commission, they have had numerous complaints against Conoco stations out here in the Denver area where inspectors have found either rotting underground tanks leading to sediments within the fuel or water leakage into the tanks and mixing with the fuel.

THIS SUCKS!!!

javanator

present. What I don't know is if the car has to be started and running for some period of time for the fault code to be captured.

Something you could try....if your car cranks, and your pump is working correctly, you are pressurizing the fuel system. You could take off the forward/front side filter connectors to see if the fuel system has been pressurized by the pump. If you have no pressure in the forward/front side filter lines, check the back/rear lines for any pressure. If no pressure is present, determine if you crossed either/both the front and rear facing fuel lines into the filter. If those check out correct, replace the fuse for the pump before assuming the pump is bad -- fuse is MUCH cheaper than a replacement pump.

<b>WARNING:</b> Wear some eye safety when you do this -- gas in your eyes is a really bad and serious thing.

<b>TIP:</b> Push the fuel line at the connector all the way towards/into the filter (this may take a little muscle with lines under pressure), then you should be able to pinch the connector much easier with your hands to disconnect it from the filter.

I don't know if this is a technically correct method to check if the pump is working or not, but it has some DIY sense to it. This actually makes sense to me to try first instead of tearing into the backseat to multimeter the pump, as a bad pump should throw a fault code.

The reason I suggest all this....I helped my buddy swap out his fuel filter on his B6S4 two weekends ago. Dummy me put the passenger side fuel pump line onto the wrong filter connector. The car cranked, but would not start. We could hear the pump each time he put the car ignition into the start position. We compared the fuel lines in-and-out of the filter on my car, and determined we crossed the rear-facing lines into the filter. We took the outboard line off the filter, no pressure. We took the center/inboard fuel line off the filter and gas sprayed everywhere. Swapped the two lines on the filter and the car started on the first crank.

MrQuA4ttro

Ok, so when I got home from work yesterday afternoon, curiousity struck--would my car start?? I figured it had been sitting for nearly 24 hours, if there was any sediment in the tank it would have settled to the bottom. 1st crank, she turns over!! aint that about a Bi***!! She ran pretty rough, and I should have let her keep running. Stupid me, I shut her down, added some octane booster to the tank--attempted to fire her up again--NOTHING!! Talk about frustration!! I rolled the car out of the garage and let it set for 4 more hours in hopes that I could turn it over again....no such luck!! Rolled her back into the garage and called it a night...better luck tonight, I HOPE!!

javanator

Sediment in your gas tank if present is never going to go away unless you get the tank cleaned/flushed. You also run the risk of damaging the fuel pump -- not certain if the pump sits between the tank and the filter, or if filter sits between the tank and pump.

Also, if you can, VAG-COM may reveal any fuel system related fault code.

MrQuA4ttro

Thanks for all the assistance! Hopefully I'll find something (as far the cause)--I'd be happy though if I didnt find anything in the tank too! I already contacted the Colorado Oil &amp; Gas commision, so hopefully they will send an honest inspector to the station I filled up at!!