F.A.S.S. where doese the air go?

[PBerry]

I can hear fuel and air when I put my ear next to filters on my fass. Is this noise from the air being extracted and returned to the tank or is it from the suction line creating the air at pickup tube?

 

[LowFly]

I can hear fuel and air when I put my ear next to filters on my fass. Is this noise from the air being extracted and returned to the tank or is it from the suction line creating the air at pickup tube?

The air is filtered in the fuel filter and returned back to the tank via the return line. The noise you are also hearing is the air that is building up in the upper part of the Water Sep. Once it overcomes the edge of the water separator nipple, it will then be drawn into the pump, making a Whooshing/gargling sound and be passed to the fuel filter where it is then filtered and sent back to the tank.