Small Engine Troubleshooting Problems? Ask a Mechanic Now.
Onan engine. Which engine do you have? B48G, or the P220G? Points and condenser, or electronic ignition?
See link above. No points, electronic ignition. Only part that seems to affect the spark by turning key on and off would be the igniter , next to the crank sensor.
I do see a condenser, I would replace it before biting the bullet for a new igniter .