National Aeronca Association Bulletin Board

Just started the new flying season today. On startup, she came to life on the 1st Pull. On runup, when switching to the RIGHT Mag, the engine Cuts off/sputters/ wants to stop, switching back to BOTH, engine runs smoothly and on LEFT, Runs smoothly. Just had Annual in December 2004, and all the Plugs were replaced. This is the 1st time since annual that the engine has been started. Any thoughts?? Could it be a switch grounding problem? I 'll contact my A&P Mechanic after the holiday.

Thanks for any thoughts.

Bill,

First thing is that I would pull the spark plugs out and check them. Could have one or more with deposits on them that have shorted them out (usually the bottoms) and causing it to act like this.

Joe A

Bill Redditt wrote: This is the 1st time since annual that the engine has been started. Any thoughts??

After annual last thing ran engine, check mags and static rpm - them put
away for winter?? If so then clean lower plugs try again, moisture in mag,
corrosion in switch. Sitting idle for a long period of time can do funny
things that where not there a few months before. Our you in or outside
Erie Pa. can be hard on anyone in the winter even a Champ.

Good luck

Mike Kne

Bill,

Had the same problem last year...turned out to be a sproken impulse spring in one of the mags. Just something else to consider.

I agree with the posters above. I'd certainly pull and check the plugs first, clean, test and rotate (see if anything changes). Like Brian said, it could be in the magneto, but do the easiest things first. I would think if it was in the grounding (mag) switch, wiggling the switch in the faulty position would make the problem come and go. I don't know if I've ever seen a problem with those switches staying open, but I have seen them where they would make a intermittent ground and you'd have a "hot prop" in the "off" position. On the other hand, I've seen magnetos go bad just sitting around too. Anyway, check the easiest things first.

Bill: Depending on which mags you have, look for oil or corrosion on the points. At the same time check the point gap as being correct. If all this checks out, run a separate ground out wire to eliminate a possible switch , wire issue.

Could be moisture in the cap area of the mag. A hair dryer will dry it out. Of course as mentioned check the plugs first, and go from there. Also check the strength and colour of the spark. If it is yellow and weak, look for a bad condenser. The spark should jump a 1/4 inch with aggressive prop swinging . Pull all the top plugs first before doing this as a safety measure.

I doubt it's a coil, as heat will usually show it's flaws first.

Ron

Had a similar problem once and found the points to be badly corroded.

Like Shorty, the same thing happened to my Eismans.....corroded points.

nkh