1975 Dodge Dart Fuel tank issue

I have a 1975 Dodge Dart Sport 360 and I cannot get more than 20-25 litres of fuel into the gas tank. The charcoal canister is long gone, the vent line is connected, but someone along the way (likely when they removed the canister) got rid of everything else and just left the steel line open on on the inner fender. I suspect that the fuel tank cannot vent the air out of it, hence not allowing the tank to fill with fuel. I cannot find a replacement canister, nor anyone who re-manufactures them, is there another alternative? Thanks in advance.