How to Troubleshoot a Small Engine Ignition


Make sure that the throttle control cable is lubed and properly working before proceeding. This procedure is for a one-cylinder engine which therefore uses one spark plug. Remove the spark plug and visually inspect for a burnt or fouled plug. Replace the plug if necessary. Inspect the ground wire carefully. It's very important to find any splices or cuts. Remove the shroud cover and inspect the flywheel and coil. Replace the coil if you find any cuts or splices in the coil wire.


Unscrew the nut at the end of the crankshaft, then use the pulley to remove the flywheel. Carefully remove the shaft lock key to loosen the flywheel. Check for rust or corrosion. Use a fine emery cloth to wipe clean the magneto magnet which is built into the flywheel.


Visually inspect the points to see if they are properly working. Do this by turning the crankshaft in a clockwise and counterclockwise movement. Points should close and open. Do not touch the probes with your fingers, as you risk contaminating them. File points with a fine emery cloth and re-gap. Reassemble.

Troubleshooting a small-engine ignition is an easy five-step process. Small engines are made only in a side- or downward-shaft design and are used in riding lawnmower tractors, hand-push lawnmowers, rototillers and lawn edgers. This procedure applies to both types of engine.