Wow!!! Have I been chasing my tail!! Additionally, I have been asking for help without giving enough information. So, here are the fact as provided by some logical diagnosis, along with a discovery. This took some time, as the condition is intermittent, and once the engine spins up nicely, I have to wait until several hours later to make additional tests. You guessed it, it has been an all-nighter.
I first spun the starter by applying 12 volts directly to the starter positive lug. The results were that it spun up fine; no problem. That eliminated the starter, and the sprag clutch.
Next test; I placed a jumper directly to the starter solenoid coil circuit ( the small push-on post). The solenoid did not buzz. It offered solid clicks each time that I applied 12 to it. Again, no problem. Starter solenoid looks good.
Next, I went back to the key switch, master on, ignitions off, and I got the prop stall, and buzz from the start relay. Only this time, I happened to be looking at the key switch, and noted that the spar pin light was flashing intermittently, and in time with the starter solenoid chatter. After a few seconds the spar pin warning light remained off, and the engine spun up just fine. So, the problem is in that spar pin circuit somewhere. It isn't on when I turn on the master, nor has it ever come on in my 120 hours of flight. The problem is in the key switch module that houses a relay for the spar pins. Bottom line, it is not a Rotax problem. It is an RV-12 problem with the spar pin circuit. Thank you all for your effort to solve my problem. My hat off to the helpful folks on this forum. I will follow up with a post after identifying the culprit, even though it is solely an RV-12 issue. FYI: Spar pins are associated with the removable wing feature that comes with the RV-12.
I am so excited to know that my problem is not sprag clutch oriented, and I am sure that I will get to the bottom of this.
Thanks, ever so much for all your thoughts, and help..............Tom
