filler neck modification

I can hold the nozzle at any angle, pump at any speed, and only get about six gallons in before having to wash gas off the quarter panel.

I still don't see a definitive answer, either. I could live with backsplash if I could get the tank anywhere near full, first.

The vent on the tank is not clogged, I do not have a return line or charcoal cannister.... but why would the vent care where it vents to?

I like to think I'm reasonably intelligent, but I just don't get it...so far.