Supposed to snow tomorrow but I can't fill the truck up 'cause it leaks gas from the filler neck. I got a new one. Mopar. I got the old one off. New return line snaps onto the tank just fine. The new main line looks like it's the right thing but I can't get it on there securely. The part sticking out of the tank is clean and in good condition. I pressed my feet against a wall while holding back the snap clip. I let it snap in place, but I can still pretty easily pull it back off without holding the clip back. What do I do? I really want to get this fixed for the snow.

Thanks!