Fuel Filler Cap: Description and Operation

FEATURES
The fuel tank filler cap has the following characteristics:

- It contains an integral pressure and vacuum relief valve. The vacuum valve:
+ acts as a secondary point for air to enter the fuel tank to replace the fuel as it is used.
+ opens only in the event that the primary entry point through the carbon canister and evaporative emission valve become restricted. The vacuum relief valve opens after vacuum in the fuel tank reaches -3.4 kPa (-0.5 psi).
+ the pressure valve acts as a backup pressure relief valve in the event the normal venting system is overcome by excessive generation of internal pressure or restriction of the normal venting system. The pressure relief range is 11.1-14.4 kPa (1.6-2.1 psi).

- Damage to the fuel tank filler cap, or contamination that stops the pressure/vacuum valve from working may result in deformation of the fuel tank. Care should always be taken to use a proper fuel tank filler cap in good working order.

- The fuel tank filler cap is a one-quarter turn design.

- The fuel tank filler cap is attached to the vehicle with a strap using the fuel tank filler pipe-to-housing screw at the three to four o'clock position.