Lawn Mower Repair - Checking the Spark Plug
In this section we are looking to make sure the spark plugs are working so before we get into the details: WARNING: Spark plus fuel = explosion. Make sure there is no gas in the vicinity when performing any spark tests!
First, if your mower is a fancy one if will probably have an ignition system. If you have on make sure it is turned on. Locate the sparkplug on your mower.
First we want to make sure electricity is getting to the spark plug. To do this we are going to be looking to see if we can see a spark so you may want to do this in a shady or darks spot. Remove the wires from the top of the spark plug and find an insulated screw driver that will fit in the socket and push it in. Find a clean place on the metal body or frame of the lawn mower (once again make sure there is no spilt fuel) and place the metal of screw driver as close to the metal of the body as possible without touching it. Have someone else crank the engine while you look for a spark. If you don't see a spark, you have a problem with the wiring or the ignition system. If you see one great, move onto check the plug.
Next, to check the sparkplug, undo the plug from the body and reconnect the wires to it. Place the end of the plug on body or frame. Now the spark in the spark plug crosses a very small distance so you will have to keep a good eye of it. Get someone else to crank the engine again and watch for a spark. Once again crank a few times to make sure it is regular. This time while watching take a note of the colour. If you see a blue spark, then you have a good spark and you can move to the next item to check.
If you see no spark, a weak on or a yellow one, disconnect the plug and clean all the terminals and reconnect and try again. Also, crank the mower again and make sure the blades turn. If you still don't get a good spark, don't mess with the old one just replace it (they are only one or two dollars) and test again.
If your mower is still not working and your spark plug works move to the next step.
Has this fixed the problem? If this hasn't try the next step.