I don't have an Onan but a Kolher and have had several issues with it and don't know if this will help or not. Does your model have a magneto? The thing in your photo looks like an ing module that connects to your coil. There is a gap that has to be maintained between it and the magneto I used a match book cover to set the gap. It is magnetic and was hard to use a steel feeler gage. This system replaces the rotor and points on the older system. If there is no gap just like points on a old car or lawn mower there will be no spark even if the coil is good.
