Fuel return lines... submerged at bottom or dump at top?

[erasedhammer]

I've been doing research on how fuel lines are plumbed at the tank and I was wondering what exactly is required for the return line.
Does it need to terminate at the bottom of tank submerged in fuel? Or can it just terminate at the top of the tank in air?

I am installing a new main tank in the bed of the truck, so the level of the fuel will always be higher if not equal to the height of the fuel lines on the engine. (Maybe lower if driving up a steep hill?)

 

[Barrman]

It has been a few years since I had one apart. However, I am pretty sure it just dumps the return on top. When I added a 6.2 to my M715. I made the fuel tank vent to the air filter on a stock truck my fuel return line. That dumps fuel into the fuel filler neck on that truck. Almost 8 ye and working great.

 

[frank8003]

Artic heaters and all normal fuel back to tank dumps are in the top, not reverse pressure of any kind. Don't know about the fuel rail stuff, double pumps and such, don't know.