fuel pump noise

[Jama665]

Ok I have a strange noise, thinking its a fuel pump. Sounds like its picking up air. I'm assuming that it has two pumps one to feed the engine pressure and one to balance both sides of the tank. No change in performance. It's intermittent. So at the moment I'm thinking it could be the second pump on all the time when I shouldn't be( if there is one).

Any ideas, 2001 1.8t AVJ(so no fuel return) quattro.

 

[Jama665]

So does anyone know if there is two pumps.

 

[Jama665]

Ok so only one pump. Opened the tank up. There is air bubbles coming out of the relief valve. So getting air from somewhere. The other side of the tank is pretty dry, so I guess its getting air from that side.

Anybody aware of how the system works. Regarding how it draws fuel from the other side of the tank.