[cparke]

Trying to follow the repair instructions to do this at newtis.info: 16 00 005 - Draining and filling fuel tank. However, I find them a bit cryptic.

Tank is full. I'm doing this with engine off to get started. I can get my siphoning tube down the fuel filler about 45", which is most of the way, until I start hitting a resistance. The tube then comes back out totally dry!

There are two pieces to the fuel filler neck, a plastic tube than runs mostly straight down from the gas cap, and then a rubber tube at the bottom of it making a 90 degrees turn connection into the tank.

Seems like there is a check valve of some kind at the bottom of the plastic fuel filler tube? I can't imagine how there would be no fuel that low down otherwise, so I'm having trouble believing this is just the 90 degrees turn rubber tube and I need to feel for it. I don't have any good pictures or information about the fuel filler neck part itself, and the repair instructions don't seem to mention anything about a check valve in it (although they have an "N51-only warning", the scope of which is unclear and they provide no alternative for other engines).

Can anyone comment on the fuel filler neck design and/or entrance into the fuel tank here? I saw the video of a fuel tank cut open, which looks like a double toilet with an amazing amount of equipment inside, but the the port for the fuel filler entrance looks just like a simple hole.

The best alternative that I can think of if getting fuel out through the gas cap port is to either disconnect the fuel filler neck at the tank and let it drain into a bucket, or disconnect the fuel hose underneath the car behind the front left tire and then run the fuel pump to get the fuel out. Both methods, however, are more intrusive and messy than I really want to undertake.

[smass]

Another option is to partially remove the fuel pump and syphon out from the top. Pop out back seat lower cushion. Remove screws on cover. Remove retaining ring. There are a lot of youtube videos on E90 fuel pump and or regulator replacement that will show how this is done. Removing both the pump and regulator would allow you to get the fuel out of both sides.

[cparke]

Originally Posted by smass

Another option is to partially remove the fuel pump and syphon out from the top. Pop out back seat lower cushion. Remove screws on cover. Remove retaining ring. There are a lot of youtube videos on E90 fuel pump and or regulator replacement that will show how this is done. Removing both the pump and regulator would allow you to get the fuel out of both sides.

Yes, but I think that is even more invasive. Remember, my tank is full not empty already. And the fuel pump parts could be fragile, as there are reports of fuel leaks from hairline fractures in the plastic cap. If I were to go that route, I'd probably opt instead for the opening at the left fuel level sender and siphon out from there, less equipment on that side.

My main question, however, is what is it about the fuel filler neck or entrance to the fuel tank that is blocking me from getting in and from the fuel getting out? Is there really a check valve in there? (if in the plastic fuel filler neck, I think it's a bit of a weird place to put it, a better place would have been into the tank side itself so that if the rubber hose gets cut, you only have a fuel leak when filling at the station)