Gas filler problem

I have a 1979 jeep wagoneer, when I try to put gas in it, the gas won’t go in. I even tried a funnel with a longer tip to get it past the flap thingy. It ran out of gas in driveway so I’m using a gas can. when I open gas cap, gas comes out. one time at pump it did this as I was filling it too.

I’m trying to sell this thing so quick cheap fix to get some gas in it would be best.

In order to put gas into a gas tank the tank must vent. There’s two ways this is done. Either there’s a seperate vent line coming from the tank that attaches to the fill neck, or there’s a hose within a hose at the fill neck.

With a seperate vent, it’s pretty easy to check if the vent line is restricted in some way by inspecting the lines from the tank to the fill neck. With a hose within a hose vent system it’s not so easy to inspect. In this system, there’s plastic tube that attaches to the fill neck and hangs down into the tank. This delivers fuel into the tank. On the outside of this plastic tube is another rubber hose. This is the one that’s seen from the fill neck to the tank. This is the vent hose. If the inside plastic tube has broken away from the fill neck and has fallen into the tank, you’re now trying to fill the tank thru the vent hose. When this happens the tank can’t vent as fuel is introduced. If the vehicle has this type of venting system to the tank, the only way to check if the inner plastic tube has broken off is to remove the rubber hose from the fill neck, and then remove the fill neck from the vehicle to determine if the plastic tube is still attached to the fill neck.