My buddy is having an issue with his 16 flss basically back pumping the gas through his gas cap while the bike is running. He had just filled it up so could it be an issue of being over filled or is there another issue we should address? Has anyone had this issue? Thank you for any help

 

Mine did the same thing after installing a tank lift. I needed to extend the tank vent tube which I replaced the original molded tube with a non molded. The bend caused the restriction. Check for something restricting the tube. Mine is under the tank speedo cover. Mine would push gas out of the cap when filled and slightly under. Good luck!