Pressure and Vacuum Relief System

In warm weather, the fuel in the fuel tank expands in the heat of the day and contracts at night. This causes pressure to build up in the fuel tank as the fuel expands and vacuum occurs as the fuel contracts. To prevent this expansion and contraction from causing the fuel tank to burst or collapse, pressure and vacuum relief are provided.







The fuel tank filler cap provides for both pressure and vacuum relief through the two valves internal to the fuel tank filler cap.