For the internal engine inside your Craftsman lawn mower to combust, it needs four crucial elements: fuel, air, spark and compression. Each element plays an integral role in the combustion process and it only takes a slight imbalance to throw the entire system out. Find the missing element in the combustion process and you can locate the source of the starting problem in your Craftsman mower.
Most lawn mowers use the same kind of fuel as your car or boat. However, lawn mowers get used less often, and owners often purchase fuel for the next use, which gets left in a can in the garage for months, even years. Unfortunately, gas goes bad after about 30 days. If used in the Craftsman lawn mower’s engine, it will likely leave behind gummy deposits throughout the entire fuel system. These deposits will gradually choke the fuel supply and shut down the engine.
Start at the tank and make sure fuel can move unimpeded to the carburetor. Clean the fuel tank, replace the fuel filter and fuel lines if gas can’t reach the carburetor. Pull the carburetor out and clean it if fuel problems persist.
After the fuel reaches the Craftsman's carburetor, it mixes with air before getting sent off to the cylinder for combustion. Once the fuel ignites, the heated gases must escape for the process to begin again. If the air cycle, just like the fuel, gets interrupted, the engine will shut off. Most air restrictions occur at the air filter. Therefore, clean the foam element of the filter in soapy water after every 10 hours of use. Clean the muffler and spark arrestor screen every 50 hours of operation.
Once the air and fuel combination reach the cylinder, an electrical charge fires off the tip of the spark plug. This charge ignites the fuel and further powers the up and down motion of the Craftsman mower's piston. Originating from the module, this charge must travel up the plug wire to the spark plug. If this current gets interrupted anywhere throughout the circuit, the spark will no longer discharge across the plug.
Common sparking problems include fouled plug tips, loose electrical wiring, faulty flywheel magnets and a loss of impedance in the ignition coil. Allow a Craftsman professional to service the high-voltage areas of the ignition system.
Related to the air system, compression creates the necessary vacuum pressure needed to keep the gas flowing and the engine moving in your Craftsman mower. Without compression, the major systems in the engine will automatically shut down. However, if a leak erupts in this internal airtight system, the engine will start losing power as the combustion process gets interrupted. Compression loss can be difficult to isolate and diagnose. Most often, compression problems require lengthy and expensive repairs. Allow a Craftsman service professional to make these repairs.