How to Troubleshoot a Ryobi RT190 Lawn Mower

Check the fuel levels of your Ryobi RT190 lawn mower. Ensure there is gas in the engine.

Open the hood of your Ryobi RT190 lawn mower to access the engine if the mower is cranking but not starting. Check your spark plug. If the black plug wire connecting into the spark plug is not securely in place, reinsert it. If the wire is in place, disconnect the spark plug and remove it.

Connect the plug wire to a new spark plug. Close the Ryobi's hood and attempt to crank and start the mower.

Open the Ryobi RT190 lawn mower's hood again if the engine still won't start. Follow the plug wire to the back of the engine assembly, where it leads to a circular part known as the magnetic coil. Positioned behind the coil is the flywheel. The slight gap between the two parts is known as the air gap. Measure the air gap and ensure it is between 0.010 and 0.015 inches. This is an incremental measurement, so take care to be accurate. You may use the thickness of a business card as a helpful guide as to how wide the air gap should be.

Loosen the Ryobi RT190 lawn mower's magnetic coil with your wrench if the air gap is not the correct width. Reposition the coil as necessary and remeasure the gap. Ensure it is now the correct size.

Replace the hood of the Ryobi lawn mower and crank the engine. It should now start.