i have a 1998 audi a4 quattro with the 2.8 motor everytime i put gas in my car it will not start i have to let the motor turn over for about a min then it will start run rough a min then it's fine until i get gas again any idea on what this could be?

 

My '99 burps 3 times and then runs fine, it does start right up though. I noticed this even if I don't fill it up all the way.

 

same here no matter how much i put in it acts this way.

 

most likely evap canister problem, I had that happen a few years ago. I could only fill up the gas tank 2 gallons at a time and the engine would have to turn over a little while before starting.

 

It is most likely the EVAP purge valve right behind the air filter box, or the one way check valve connected to the purge valve. The valve is about 50 dollars and it is a 10 minute DIY replacement.