Since I have never had mine out, looking at YouTube videos for Volkswagens, how about putting the seal in the tank first, then putting the fuel pump in?
I wondered that too. Putting it in the other way doesn't seem to have any chance of working. There is a second lip inside the hole the seal sits on. If it was upside down it would just crush up against it.
I've had the seal in twice now. Both times fuel still leaked. On the way back out, the seal seemed like it was in good position. There wasn't any signs of folding or damage to the seal.
The snap ring doesn't feel like it puts enough pressure on the top of the pump to me. The pump also seems a little loose in the hole. Is it possible the hole in the tank is too large?
that is a good opinion, since I am sure the pump is the same one on your old tank.
take a measurement and see if the service center still has you old tank to compare to.
This is finally resolved. I thought I'd post what I learned in case any other mechanically inept soul gets stuck doing this.
1. Get two new seals instead of one. Inevitably the first will fold over. It gets harder to get right every time you get it wrong.
2. Use a sheet protector like Graeme mentioned. Cut the bottom off and treat it like a plastic sleeve.
3. Lube everything. Lube between the seal and the pump. Lube the outside of the seal. Lube the tank mating surface.
4. A seal that is folded will push the pump to one side. If the gap around the top of the pump (which is quite small anyway) isn't even, the seal is likely folded
5. If the pump won't rotate in the hole after it is fully inserted but before the snap ring is in place, the seal is likely folded.
6. If you have to make another attempt and you filled the tank with fuel, let the seal dry out for several hours and then toss it in the fridge in a ziploc bag. Each time the seal comes in contact with fuel it expands and gets much harder to get in.
All in all it took me 11 attempts to get the seal installed correctly. 165 gallons dumped in the tank. 155 pumped out (left 10 in the final time to go to the track with).
