Fuel Filler Cap: Description and Operation

Fig.32 Locking Fuel Cap:

FUEL CAP LOCK CYLINDER
Some vehicles are equipped with a locking fuel filler neck cap tethered to the fuel tank filler neck (Fig. 32). This limited factory installed locking fuel cap utilizes the standard vehicle key to lock and unlock the fuel cap from the fuel tank filler tube.

A locking fuel filler neck cap is utilized to prevent refueling the vehicle with the ignition ON, theft or contamination of the vehicle fuel supply The standard vehicle ignition key is used to lock or unlock the fuel filler cap. By inserting and rotating the ignition key to the right, unlocks the cap. Rotating to the left, locks the cap.

FUEL FILLER CAP
The plastic fuel fill cap is threaded/quarter turn onto the end of the fuel filler tube. It's purpose is to retain vapors and fuel in the fuel tank.

The fuel filler cap incorporates a two-way relief valve that is closed to atmosphere during normal operating conditions. The relief valve is calibrated to open when a pressure of 17 kPa (2.5 psi) or vacuum of 2 kPa (0.6 in. Hg) occurs in the fuel tank. When the pressure or vacuum is relieved, the valve returns to the normally closed position.

CAUTION: Remove the fuel filler cap to release fuel tank pressure before disconnecting any fuel system component.