Alright, so I'm new to this.. Names Mike. I have a 2000 Mustang and just replaced the whole filler neck and grommet. I go to fill it up, and no more than $1.50 in, the fuel starts backing up all the way out of the top of the filler! before I changed it, I noticed the grommet could use replacing, but also that the fuel neck itself was rotting out. I figured this was the reason that fuel was backing up/shutting off pump/leaking.. Now I notice that there's obviously some kind off back pressure or something not allowing the fuel to flow into the tank.. took me like 3 minutes to get $5 in it!!? sensor??? shut off switch/valve???? some type of blockage/something clogged?? idk, need help asap