How do I troubleshoot if the Craftsman M220 engine won't start?

Check if the spark plug wire is disconnected and reconnect it if needed. Verify the engine is primed by pushing the primer bulb. Inspect the spark plug and replace it if defective or incorrectly gapped. Ensure the fuel tank has gasoline and check that the ON/OFF switch is in the ON position. If the carburetor or fuel line appears dirty, clean them. Replace the air filter if dirty, and drain and replace any stale gasoline with fresh fuel.