If it was working and now it's not the vent hose in the filler neck popped loose. Just reinstall it and you're done:

 

That what I going to do first. I got to drop both the rear leaks above 3/4 I think it is the lock ring gasket. I going to drop them next week after I help a friend finish moving

 

Hi new member here so I am having the same issue with not being able to get fuel into either tank on my 1996 f250 4x4 7.3l powerstroke known as Ruby Rose there for my chosen user name but anyway If I was to eliminate the inner tube of the filler necks on both tanks would it help eliminate the venting issue? Are there other tricks I could use I hadn't had any issues until recently now both tanks are a absolute struggle to fuel up any advice is appreciated and thanks in advance