How to Install a Gas Cap like a Mechanic

Standard Gas Cap

1. 1
   Twist off the gas cap. Rotate the gas cap counter-clockwise until you are able to lift it away from the opening of the fuel tank.

   • Set the old gas cap aside. Keep it until you have installed a new cap. If the new cap does not fit your fuel tank for some reason, you should cover the fuel tank opening with the old cap until a better replacement can be found.
2. 2
   Remove the leash. If the leash is still connected to the gas cap and the fuel door, you will need to remove that, as well. ^[3]

   • It can remain attached to the fuel cap, but you must locate the locking peg attached to the opposite end of the leash and pop it out of the hole in the fuel door.
   • Press up on the bottom of the locking peg until it unsnaps from its place in the door hinge.
   • After removing the gas cap and the attached leash, you can install a new cap.
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Pressure Release & Quick-On Locking Gas Caps

1. 1
   Insert the key. Insert the gas cap key into keyhole on the handle of the cap.

   • You will not be able to remove an old locking gas cap without first using the key to unlock it.
2. 2
   Rotate the key to the left. Turn the key in a counter-clockwise motion to unlock the gas cap. You should only twist the key one-quarter of a turn; do not twist it any further than that.

   • Hold the gas cap still as you turn the key.
   • For quick-on locking caps, you can proceed directly to the next step after unlocking the cap.
   • For pre-vent (pressure release) locking caps, you must allow the pressure to release before continuing. Listen for the sound of hissing. Wait for several seconds until the hissing stops completely before moving onto the next step.
3. 3
   Rotate the cap further to the left. Grab the gas cap handle and continue turning the cap counter-clockwise.

   • Do not use the key to rotate the cap.
   • Continue to twist the cap until it is completely loose. At that point, you should be able to lift the gas cap away and set it aside. It is a good idea to keep this old gas cap until after you are certain that the new gas cap fits.
4. 4
   Remove the key. Once the gas cap has been removed, you can remove the key by rotating it one-quarter turn to the right and pulling it straight out.

   • After you complete this step, you should be ready to install a new gas cap.
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Metal Push-On Locking Gas Cap

1. 1
   Insert the key. Fit the gas cap key into the keyhole located on the outside of the cap.

   • You'll need to use the key to unlock the old cap before you can remove it.
2. 2
   Rotate the key to the left. Twist the key one-quarter turn in a counter-clockwise direction.

   • This action unlocks the gas cap. As you rotate the key, the lock bars inside of the cap should retract, freeing the cap from its usual place.
   • Hold the cap still with one hand as you unlock it.
3. 3
   Lift the cap away. The cap should be completely free at this point. Remove it by simply lifting it away from the neck of opening of the fuel tank.

   • Keep the old cap until you are certain that the replacement cap fits and can be installed properly.
   • After lifting the old cap away, you can install a new gas cap.
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