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My friend's legacy Sonex with Aerovee Turbo was going through a prop balancing session last week on a 95-degree day making multiple wide-open runs. The sequence of events are as follows:

Start, run, adjust weights, start, run, adjust weights, etc. Towards the end of the session, it started to have problems starting which got worse with each attempt. Finally, it would not start at all. We all figured it was just too hot and left it alone. The next day and currently, it will not start. It turns over, fuel is flowing, (although the bottom plugs are dry), and we discovered that we are not getting any spark to either ignition systems spark plugs.

We ohm'd out the coils and compared them to four other coils that we know are working. The coils, (identical brands and models that we know are good), were identical in ohm readings, my friend's coils readings were vastly different, lower, so, as I had a spare set of new ones, we replaced the coils. Still no spark.

Inspected the wiring, switches, fuse, grounds, and still get no spark from either ignition system. Inspected the adjustable timing cap and noticed slight rotational scrape marks around the circumference but it is not touching anywhere while hand turning the engine. The magnet was still in the cap.

I don't know how to test the magnetrons or the coil triggers.

I have not seen both systems fail before and we are looking for some ideas from the group.

Its probably your CHT probe on the Antenna base. I warned you about EMI issues ;)

Scott

Its odd. About 10 years ago I had a trigger fail on mine. The sensors had moved (screws sheared per SB) and touched the trigger killing the magnet in it. It still seemed magnetized but Scott Casler suggested changing it (I went to see him to get a new sensor also) and it worked. Its odd the Magnetron is not sparking either. I have found mine is hard to start, if not impossible sometimes, on just the Magnetron. It has to be something simple. Keep us posted.

Scott

Scott,

Thanks, it seems you are correct as my friends' turbo now starts and runs fine! WTH??
Actually, it was the bad coils. He replaced them with my spares and it started up and ran fine. Someone suggested that the magnetrons couldn't generate enough power to start the plane alone with only the rpm the starter could provide. I don't know if that is true. I never tried to start on mags alone.

In any case, it took less time to fix than it took me to ask you guys for help.