The fuel pump would shut off when refilling at gas station. Took so much time to get the tank full.
I found this write up that explain what happened and how to check the canister.
http://forums.audiworld.com/showthre...2343265&page=2

So, I need a new or used canister as above link mentioned. But I can't find exactly which one should I get by search '04 a4. So I went to remove the canister, and parts number on my canister is 8e0201799 and it has a small carbon filter 8e0201801d connect to it.
And then googled those 2 number only to found some russian audi forum. What happened here...?
Anyway, I check it out and finally found the brilliant solution to solve the refilling problem.

If you like me that have the canister 8e0201799 and carbon filter 8e0201801d. You can cut the filter open, clean the filter net with carburator cleaner, and glue it back together.
Make sure it's fully seal before you put it back on car. Or you'll have CEL for evap leak like I first time did.
Here is the link
http://www.audi-club.ru/forum/showth...142000&page=12

Now I don't have to keep remove the nozzle when refill.
Just need to remember no more top off the tank.
Hope this would help someone.

 

For what its worth...my A4 was hard to refill at the gas station...multiple shut offs on the pump. Went to the dealer and bought EVAP Canister 8E0-201-801-L and the Hose audi now recommends replacing the charcoal filter 8E0201801D hanging on the side of the canister. I noticed that my canister felt very light so checked the charcoal filter by blowing thru it both directions....it was blocked . The hose PN 8E0-201-946-H replaces that little side filter...its pricey at $65.18 but I think it has done the trick. Good luck.