adm has 2x6mm and 1x4mm line
6mm Vent
6mm Feed
4mm Return
Find out which line is the vent then you know which is the feed. If its still mounted in the original car with all the lines hooked up, just get under it and trace it back. If not, get a lift pump connected to one of the 6mm pipes. If it doesn't get fuel out in a few seconds, its a vent.
Also, try googling images of "ae86 fuel tank", a lot of pics come up with things to help you