Cannot fill the gas tank?

Most likely, the problem is the breather tube. If you look under the vehicle, you will see the filler tube that you place the fuel into. The fuel runs through there and into the tank. However, when the fuel enters, air has to be released for the fuel to enter. Along side the filler tube, you will see a small tube. THat is the breather. It allows air to exit the tank when you fill it. Chances are it is damaged, clogged, or crushed. Check it out and if needed, remove it from the tank to check if air will blow through both the tube and make sure there is nothing blocking where it enters the fuel tank.

It can be a pain, but that is most likely where the problem is coming from.

Let me know if you have other questions.
Joe