Help ! 72 won't accept fuel

[rod murphy]

I am not able to get fuel into the fuel tank on my 72 . It is a new rear mount poly tank and the filler hole is on the left rear side about 2 inches higher than the clearance light. It is well vented to the atmosphere with two seperate vent hoses and the fill pipe/hose has a smooth transition down to the tank. I can put fuel in with a gas can........but when I try to fill it at the pump gas just spits out and the nozzle keeps snapping off. Anyone have any ideas ????????