Checking Spark

Checking spark is easy, once you know how. If you have not watched the video that explains how to remove your spark plug, now would be a good time to do so.

Once the spark plug has been removed from the engine, push the spark plug back into the rubber boot until it seats firmly. Next, rest the metal end of the spark plug against the engine. There must be a metal to metal contact between the plug base and the engine, so make sure it is not touching a plastic part of the engine. Make sure the throttle control is in the ‘on’ position, and any safety switches are shut off. The choke should also be in the 'off' position. Pull the starter rope or turn the ignition key. A periodic spark should be seen arching cross the electrodes as the engine turns.

Example: Most lawn tractors will not start unless someone is sitting on the driver’s seat. When checking for spark, make sure you are sitting on the seat.

Example: Most walk behind mowers have a handle lever that must be held down for the engine to run. Make sure this is held in place while pulling the starter rope.





Checking the spark on an engine may be dangerous. If the engine is flooded, placing the spark plug next to the spark plug hole on the engine head can result in a fire.To avoid this disaster, move the spark plug away from the hole, or let the engine sit for about 60 minutes to let the excess fuel evaporate. Having a fire extinguisher close by is also a good idea.

It also helps to be in a darker location when watching for the spark at the plug. Being indoors is usually adequate.

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