Fuel Filler Cap: Description and Operation

Fuel Filler Cap:

DESCRIPTION
The fuel filler cap is a pressure-vacuum type. A built-in torque-limiting device prevents overtightening and also eliminates the escape of fuel vapors. To install, turn the cap clockwise until a clicking noise is heard. This indicates that the cap is fully seated.

A vacuum relief valve is incorporated into the fuel filler cap. If the pressure in the fuel tank becomes negative (vacuum), the relief valve opens to release the pressure created within the fuel tank. Only when vacuum becomes excessive within the tank does this occur. Vacuum pressure is also vented through the Tank Pressure Control (TPC) valve which is located next to the EVAP canister.

A pressure relief valve is also located in the fuel filler cap. If the pressure of fuel vapor within the tank should exceed that for which the fuel system is designed, the pressure relief valve opens, and excess pressure is vented to the atmosphere.

NOTE: If a fuel filler cap is to be replaced, use only a cap with the same features. Failure to use the correct cap can result in incorrect operation of the fuel delivery system.