trying to get to the bottom of this problem i replaced my rear tank cause it was leaking put everything back up figured my probelm with the tank spiting fuel out of the spout but it wasnt and i connected the filler neck the same way i took it down and it still spits fuel up threw the filler neck but the front tank can be set on the 2nd notch on the pump handles and it will fill the tank fine but the rear i have to sit their and manually feed it is it the filler neck of the vent on top of the tank?

 

See this website.

Performance Injectors for 7.3L Ford Power Strokes

 

Hutch mod and fuel filler neck mod for the win!

 

The only thing I would add to this is if you do the Fuel tank vent mod, remove the bed. its only like 6 bolts and a harness plug. you would already be removing the fill necks. pretty sure 4 guys could lift the bed off one of these trucks. got a pair of good saw horses or some milk crates to set it on? you could definitely get at everything easier. also hard tubing like copper or maybe some brake line would sag and trap alot less, and be easier to pitch correctly back to the tank.