Abstract: An improved fuel system for motor vehicles, such as motorcycles, including a fuel tank having a fueling port and a separate relief port, a cap which is adapted for closing and sealing the fueling port, a pressure relief valve for closing and opening the relief port, and a conduit for directing fuel from the relief port to a location which is away from a rider of the vehicle. The pressure relief valve has an inner orifice which is normally closed, but opens to allow fuel to flow from the tank through the conduit when the pressure within the tank exceeds a predetermined super-atmospheric level, for example, during a collision. The fuel system also provides for venting of air into the tank as fuel is consumed.