Tecumseh manufactures a variety of small engines for use in lawn and garden products and in small industrial equipment. To protect the engine and keep it operating at peak efficiency, Tecumseh engines are equipped with a governor. If the engine over-revs, the governor will cut back the throttle. Conversely, if the engine is under a heavy load, the governor will increase the throttle to compensate. To adjust the governor on a Tecumseh engine, you'll need only some basic hand tools.
Before beginning the adjustment of your machine's governor, you first need to identify it. The governor mechanism keeps your lawn mower moving at the same speed regardless of the load request. Akin to the cruise control system in your car, the governor is a critical component of a lawn mower. There are three types of governors: mechanical, pneumatic and electronic. Yours will appear as a plastic arm or flap and be located underneath the engine housing. You should be able to remove both the engine housing and governor itself using pliers and a screwdriver.
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Be sure to disconnect the spark plug whenever you work on a small engine to prevent the engine from firing accidentally while you work. Remove the spark plug wire from the tip of the spark plug and secure it away from the spark plug. Inspect the spring between the governor and the throttle lever. If it appears to be stretched or worn, replace it with a new governor spring. Rotate the throttle lever so that the throttle is in the wide-open position (for when the engine is running at top speed). Notice which direction the governor arm moves as you rotate the throttle lever.
Adjusting the Governor
Loosen the screw at the base of the governor arm with a screwdriver. Rotate the governor arm in the same direction as it moved when the throttle lever was moved to wide open. Hold the governor arm in this position with one hand and tighten the screw at the base of the governor arm with the other hand.
Reconnecting the Machine
Re-connect the spark plug wire to the spark plug and start the engine. Position the throttle to halfway open and let the engine warm up for about five minutes. Open the throttle to the wide-open, full position and listen for any cut-out in the engine. If it runs smoothly, back the engine off to idle and listen again. If there is any revving or cutting-out of the engine, repeat the previous steps.