Lawn Mower Yardman 160CC Will Not Start

Air Quantity

• The Yardman lawn mower engine needs to bring in a continuous supply of air to dilute with the fuel to allow the fuel to combust more readily. After combustion takes place, the heated gases need to get vented to make room for the next cycle of combustion. If air gets blocked at the incoming or outgoing points, the engine will likely not start or may start up and quickly die. Wash the foam element in the air filter, located near the fuel tank, in soapy water and rinse underneath cool water. Scrub out the muffler and spark arrestor screen with a wire brush.

Fuel Quantity

• Fuel in the Yardman needs to travel from the fuel tank to the carburetor, where it mixes with the air, and then off to the cylinder for combustion, while any excess, unused fuel gets expelled back to the tank. If, at any point in this cycle, the fuel stops flowing, the Yardman will not start at all. Major fuel obstructions can occur anywhere, but common sources include a dirty fuel filter, dirty fuel hoses, blocked intake and outtake carburetor bores. Any air leak into the fuel system and leakage of fuel out of the system can also shut down the engine. Check the entire fuel system starting at the tank and working up to the cylinder.

Spark Quality

• If fuel and air reach the cylinder and the spark plug discharges a lower than necessary spark, the Yardman will not start. The spark originates in the ignition module and gets sent up through the HT lead wire and on to the spark plug. Like the fuel system, a spark can get lost at any point within the system, and further complicating spark issues, the circuit may be prematurely grounded at any point in the system. Common spark problem areas include the plug, the HT wire's boot, loose wires at their connecting terminals, discolored flywheel magnets and worn out coil. Allow a professional to service the ignition system.

Other Complications

• For the Yardman to start combustion and keep the process running uninterrupted, the crankcase must generate a sufficient amount of compression. Compression creates the vacuum pressure needed to keep the fuel pump pumping and the engine running. Loss of compression can occur at many sources inside the engine. Common air leaks occur near gaskets and the crankshaft. Due to their complicated nature and possible operator injury, allow a service professional to address any compression related issues.