Connecting an in bed tank

[mpaulson]

Other than overfill returning to the tank, I don't get the point of a return line. I didn't have one on a truck that I set up as a gravity feed years ago. Or maybe in my case, with the Geno's rubber plug in the filler spout if that blocks enough air from escaping to inflate the trucks tank.

 

[Hoefler]

Doesn't over pressure the main tank, and no need to continue running the transfer pump if the tank is full.