1. Sticking Throttle: Check the throttle cable and linkage to ensure that the throttle is not sticking or binding. If it's stuck in the open position, the engine will continue to run even when you release the throttle lever. Make sure the throttle cable moves smoothly and returns to its original position when released.
2. Governor Failure: The governor on your mower is responsible for regulating the engine speed. If the governor malfunctions or becomes disconnected, it can cause the engine to run at a high speed and not respond to the throttle. Check the governor linkage for any damage or obstructions, and make sure it's properly connected.
3. Carburetor Issues: Problems with the carburetor, such as a dirty or clogged carburetor, can cause the engine to run erratically or at a high idle speed. Clean or rebuild the carburetor according to the manufacturer's instructions. Check for any leaks around the carburetor that may be causing air to enter and disrupting the fuel mixture.
4. Fuel Flow Problems: Ensure there is an adequate fuel supply to the carburetor. Check the fuel lines for kinks or blockages and make sure the fuel filter is clean. If the fuel flow is restricted, the engine may not be getting enough fuel to operate properly.
5. Spark Plug Issues: A worn-out or fouled spark plug can affect engine performance and cause it to run unevenly. Check the spark plug gap and condition, and replace the plug if necessary.
6. Check Drive System: If the wheels are not disengaged, the mower will continue to propel itself even when the throttle is released. Ensure the drive system clutch is disengaged correctly to prevent the wheels from turning while the engine is running.
7. Electrical Issues: Check the electrical system, particularly the ignition switch and wiring, to ensure everything is functioning correctly. A faulty ignition switch or damaged wires can prevent the engine from being turned off properly.
If none of these solutions resolve the issue, it's best to take your Sears 675 21 rear bagging mower to an authorized repair center or consult with a qualified lawn mower technician for further diagnosis and assistance.
