[Steeveedee]

The correct gas cap avoids this problem. If you make a right turn, it takes enough time for fuel to slosh that a trap door isn't going to help, especially, iirc, there are vent holes in the rest of the reducer in the neck for vapors to be pulled back into the vapor recovery hose. Maybe you don't have those fuel nozzles where you live- they are mostly used in high pollution areas.