How to Adjust the Idle on a 1981 Mercury Grand Marquis

The idle speed in a 1981 Mercury Grand Marquis is the rate of engine RPMs when the throttle is at rest. If the idle speed is set to low, the Grand Marquis's engine can stumble and stall. If the idle speed is set too high, it wastes gasoline and puts undue strain on the transmission when you shift from park into gear. The idle speed on the 1981 Mercury Grand Marquis should rest in between 1250 and 1700 RPMs, as indicated on the tachometer. Anyone with basic auto repair experience can adjust the idle speed on a 1981 Mercury Grand Marquis.

Tools Used: Flat screwdriver

Adjust the Idle Speed

Open the 1981 Mercury Grand Marquis's hood and support it with the prop rod. Remove the wing nut holding the air cleaner lid in place by hand. Remove the air cleaner lid by hand.

Remove the air filter and air cleaner base by hand. Start the engine.

Turn the idle adjustment screw, located on the front of the carburetor, to adjust the idle speed. Turn the screw clockwise to raise the idle speed, counterclockwise to lower it. Verify the idle is set where you want it on the tachometer.

Reinstall the air cleaner base, air filter, air cleaner lid and air cleaner wing nut by hand. Close the Grand Marquis' hood.

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