The fuel tank rollover safety valve is a brass or plastic valve located on the fuel tank.  The fuel tank rollover check valve works by way of a ball or spring inside that allows pressure and vapor to escape the fuel tank when changes in temperature occurs. The Ball in the valve moves to the closed position when the vehicle experiences a rollover; in effect cutting off fuel from exiting the tank. Most fuel tanks have a rollover valve of some kind. This article is regarding threaded brass rol … read more