Obstruction

• Before doing any troubleshooting of the mower, check the blade underneath. First disconnect the spark plug lead on the front of the engine. Then turn the lawnmower over and see if any piece of wood or metal is jamming the blade. Also, make sure the blade axle is free of any string, twine or other material that might interfere with the free turning of the blade. Check the spool on top of the Honda lawn mower engine to make sure the pull string is not knotted or incorrectly spooled. If there areas are clear of any obstruction, continue examining the engine.
  
  

Controls

• The controls regulate the power, speed and safety features on the Honda engine. Check all the cables and connections for proper operation. If the device powered by the Honda engine has a safety system, usually on lawn mower and gas powered tools, it must work properly. If not, the safety switch will prevent the motor from starting. Also, if a cutoff switch is damaged and remains in the "OFF" position the engine will not start until the switch is fixed.
  
  

Spark Plug

• Always begin by checking the spark plug if your engine won't start. As the spark plug connection wire and spark plug lead are on the outside of the engine, it's easy for something to come loose. Make sure the lead wire under its protective rubber hood is snug. Also, check the connection to make sure no corrosion or dirt is causing a poor contact. As a last step, never hesitate to go ahead and replace the spark plug. Replacements are inexpensive.
  
  

Check the Tanks

• Small Honda engines have an oil tank just like a large motor in a car. Make sure the engine has the required oil level. A low oil level can cause the piston and other moving parts to not move smoothly and prevent start up action. Of course, the gas tank has to be full. Before filling it up, however, there is a rubber hose connecting the tank with the engine. Is it blocked? If the engine can't get gas it won't run. Make sure this fuel line is clear. A small engine used outdoors can get debris in the gas tank that gets pulled into the fuel line.
  
  

Air Filter

• Air needed in the engine is pulled through a porous filter. If the filter is dirty and clogged then the airflow is restricted. Most small Honda pull-start engines use a piece of foam as a filter and it can be cleaned and reused. Also, while the filter is removed check the air inlet behind the filter for any contamination blocking the airflow.