Pressure And Vacuum Relief System

This system consists of a sealed filler cap with an integral pressure/vacuum relief valve. Fuel system vacuum relief is provided after 0.5 in. Hg, and pressure relief after 1.8 psi. Under normal conditions, the fill cap allows air to enter the tank as fuel is used, while preventing vapors from escaping. In the event of a rollover, the valve prevents gasoline from escaping.