No it could be just the pump is pushing more gas than the neck can handle. My 33 ford pickup has basically a 90 off the tank for the neck so most pumps will push way more gas than what the neck can take causing it to back up and spill. If the nozzle is held the right way I can get more gas in but it will still back up. My 68 is the same way I have to take it really slow because the pump is pumping way to much than what the neck can flow. Think of a funnel that's probably what's happening.