I'm guessing it doesn't have a vent tube? If it doesn't, I think you need one. Then you won't get that airlock. You may have to fuel it slowly, though because the weight of the fuel is what will push it past the trap. Maybe just do a test first, disconnect the fuel line at the top and see how it fills. Use a can of gas though, I don't think you want to try it at a gas station, lol.