fuel problem on 1993 Ford E-350

I try and add gas to my camper, and it will not take the gas? like something is blocking the gas from going in.

Asked by for the 1993 Ford E-350
You could have a restriction in the fuel filler tube - there is a flapper valve that could be restricting fuel flow.

Could also be some kind of fuel tank ventilation issue.
The problem is inside of the tank? Anti-syphon baffel?
Probably at the tank side of the filler neck. Can't really tell unless you get into it.