Poor Engine Performance

• Take a look at the fuel system. Is there dirt in the system or a clogged filter. If the mower has been warehoused for the winter, was the fuel drained and now re-filled with fresh? If not, it's stale and then there's your cause. In any case, It's worth changing fuel suppliers to see if the blend you are using isn't compatible with this engine.
  
  

The Engine Won't Start

• These mowers require you to depress the brake pedal when starting the engine. Check for loose spark plugs. Is the fuel the same fuel specified in the manual? Check for a plugged fuel filter. Check for electrical problems. You may even have a defective safety switch.
  
  

The Engine is Hard to Start

• The mower's operating environment is harsh---dusty and dirty and the mower is susceptible to it. Check for a dirty carburetor or a plugged fuel filter. After a long winter's storage, the engine oil could be too viscous and you might have to change it. Again, stale fuel may be your culprit.
  
  

Engine Runs Unevenly

• Check that the air cleaner element, cooling fins, fuel line or fuel filter isn't plugged. Check for a sticky choke or throttle cable. The engine missing under load is likely to be caused by stale fuel, a plugged fuel filter or by a faulty spark plug. Vapor locks can be caused by a loose connection at the fuel filter or fuel pump. The engine not idling could be a spark plug gap incorrectly set. Engine knocking could be caused by low octane fuel or low oil.
  
  

Other Engine Issues

• If the engine is losing power, check to see if there is too much oil in the engine. Also check to make sure the air cleaner isn't dirty. Is the engine using too much fuel? Check the choke. Black exhaust can be because the air filter is dirty or oil soaked. When it comes down to it, most problems with this engine will be because of dirt or bad fuel, so check those areas first.