Small Engine Troubleshooting Problems? Ask a Mechanic Now.
Welcome to JUST ANSWER small engines, let me try to help you !! I don't know it all, but maybe together we can get you a satisfactory answer!
Can be the coil failing. But spark can be affected by oil sensor or shutoff by the panel. To check you need to remove the kill wire from the coil when it has no spark, and if it still has no spark with kill wire removed, the coil is bad and needs replaced. But it it now does have spark, the oil sensor or the other generator functons can be killing the spark.
Yes, kill wire is the only wire on the coil. As for the spark when key is released is common occurrence caused by voltage feedback from condenser.
Primary wiring is the spark plug cable, the coil has another smaller wire, which is for the kill function, and has to be grounded out to kill engine. Otherwise engine could not be killed.
I will opt out. Have a great day.