I have a Briggs 23hp Vanguard in a repowered skid steer. Unit has 150-ish hours on it. I had a problem with it killing plugs (NGK's) and then a no spark situation. Pulled engine and traced that to simple rust on coils and flywheel. This is a farm machine and not always out of the weather. Out of concern about having to pull engine again, I replaced the original factory coils with new aftermarket. Re-installed and got several hours of run time. Ended up back to a no spark scenario. Pulled engine again and found no rust, no apparent cause for no spark situation. Tried engine while half out of machine and had a nice blue spark!!! Figured I must have done something to fix issue and put engine 90% of the way back in, left a hydraulic pump unhooked. Tried to move machine and it's popping and backfiring. My gut (been in the small engine/chainsaw biz 40 years) says ignition problems. I have no way to test coils. The wiring on this is pretty simple and this doesn't appear to have an instant "kill" type set up where the spark is grounded out. I'm probably having a mental block, but I'm wondering if I should put the original coils back in and check what wiring there is. I can't see where it can be anything else.
Am I over or under thinking this? Am I missing something obvious? Wouldn't be the first time I overlooked the obvious, but this is a much larger and newer engine than I'm used to playing with.