Archived back pressure in fuel tank

[mholeva]

This is the second time I pulled the same grade and had fuel blow out all over the back of the truck and trailer. Nothing unusual and not that bad of a grade. Two different trailers first one a toy box loaded the second 5x10 with two quads on it. My son did notice white smoke coming out the pipe in the middle range just before lock up. The tank wasn't topped off and when we got to the desert there was not sign of fuel. The truck has an edge nothing special 3 settings manual. the only addition to the truck was a valcan relocation kit to put the fuel pump by the tank. The tank is a 45gal after market this didn't happen before the mod,. Can a air leak cause the back pressure. It don't look like the over flow was the point of release it's coming from the rear top corner of the transfer flow tank. Are there any way to see if the tank is over pressureizing. Thanks for any help.

 

[DCreed]

try driving with the filler cap loose/off. did you crack any lines when you relocated? maybe loose injector line or pickup/return at tank(the fittings are tricky)