Rick Policelli

Fuel leak on a 69 Coronet. After filling the tank I drive the car for awhile then park. Shut off the engine. After about 2 minutes fuel begins running out of the vent hose which is up in the frame. If I remove the gas cap the leak stops.
I have blown out the vent hose and the line that runs up in the trunk. The other two lines coming out of the tank run up to the fuel filter. Seems like there is pressure building up in the tank?? There is no canister on this car.
Appreciate any thoughts on how to correct this leak.