shortbed rv

Does anyone know the return fuel line pressures on a stock truck and on the Walbro mod truck? How much pressure can you push into a full fuel tank?

On the Walbro mod:
I ask because I have a Aux tank that gravity feeds the main. Would there be a problem with the return pressure pushing the gravity feed back? I have to decide if I want to T into the return line "or" return to the filler neck. It sure does look easier to just T into the return line.

Thanks for your help

Rpainter

I ran my return line with my walbro kit to the filler neck. with a bypass if the bypass is set at 28 psi them you will have more more than 28 psi of return pressure