NB, I had that problem with my Jet Boat and the problem was the vent hose made a turn which put it lower than the top of the tank and gas would accumulate in the line stopping the venting of the air and cause it to spit gas and making it impossible to fill the tank without a mess and a smell, I raised the vent line by taking the slack out and this solved that problem, hope this help's cause that is a pain in the "boat", and dangerious also.