Why does my fast idle screw not bottom out when the engine is warm and I let up on gas peddle?

The fast idle screw is supposed to contact the fast idle cam when the gas pedal is released. When the engine is cold and the choke is on, the fast idle cam contacts the screw and opens the throttle slightly, allowing the engine to idle at a higher RPM. As the engine warms up and the choke is disengaged, the fast idle cam pulls back and the screw should make contact and hold the throttle open slightly, allowing the engine to idle at a normal speed.

If the screw is not making contact with the cam, it may be out of adjustment or worn. To adjust the fast idle screw, turn it clockwise until it contacts the cam. Then, turn it back counterclockwise until the engine begins to idle at the desired speed.

If the screw is worn, it will need to be replaced. To replace the fast idle screw, follow these steps:

1. Disconnect the battery.

2. Remove the air filter housing.

3. Locate the fast idle screw on the throttle body.

4. Use a wrench to loosen the locknut on the screw.

5. Turn the screw counterclockwise to remove it.

6. Install the new screw by turning it clockwise until it is seated in the throttle body.

7. Tighten the locknut on the screw.

8. Reconnect the battery.

9. Start the engine and let it warm up.

10. Adjust the fast idle screw as needed.