Secondary Ignition Stopped Working

[pilotyoung]

Thanks for the answer. I will look next time I go to the hangar.

[pilotyoung]

Well I am here asking for help again. Today I went to the hangar and confirmed that the magnet is still in the trigger cap. I also confirmed that the fuse for the secondary ignition was blown. It has blown two fuses. I replaced the fuse and then confirmed that I had 12 volts on the side of the coil that it is supplied to. It was in the 30's and I have the upper cowl off so I did not try to start the engine.

So it is blowing the fuse when the engine is running. I am wondering if anyone else has experience this problem. As I look at the diagram the only thing that comes to mind is a bad coil internally and it showing up when it gets hot and then blows the fuse. Another option is a nick in a insulation on a wire and when vibrated it is shorting to ground.

My thought is next time I am at the hangar is to disconnect the wires from the coils and measure the resistance with my ohm meter and see if one is shorted or if there is a major difference between the two coils.

So if any of you have experienced this problem and solved it or if you have better trouble shooting ideas, please let me know.

Thanks.

[Rynoth]

What size is the fuse?

viewtopic.php?f=21&t=5506&hilit=fuse

[pilotyoung]

10 amp

[sonex1374]

John,

The secondary ignition system can sometimes position itself such that the trigger magnet and triggering module are aligned such that electricity is continuously flowing through the coil. This can overheat and damage the components, or blow the fuse. This may be what happened to you. Try replacing the fuse (you might go to a 15 amp instead) and make it a practice to only have the secondary ignition turned on when the engine is running. Don't leave the ignition powered up while sitting on the ground with the engine stopped. This could happen upon shutdown if you kill the engine with the mixture and then get distracted doing other post-shutdown stuff while the panel or ignitions are still on.

Jeff

[gammaxy]

The secondary ignition system can sometimes position itself such that the trigger magnet and triggering module are aligned such that electricity is continuously flowing through the coil.

When the magnet aligns with the trigger, the current through the coil is forced to drop from ~3.5A to ~0A. It's infact more likely it randomly positions itself such that no trigger is aligned with the magnet and you have electricity continuously flowing through both coils. In my experience, though, after a somewhat brief period of time (several seconds?), the triggers automatically stop sinking current through the coils if the engine is not running. Interestingly, this means the spark plugs won't fire until once the coils have been re-energized after one complete revolution of the engine. Might be good practice, then, to only switch the secondary ignition on just before engaging the starter.

Measuring the resistance of the two coils is a good idea. I believe it can be done reasonably accurately without removing them from the system as long as all the electronics are off. Mine are about 3.2 ohms each. If you measured ~2.5 ohms, I'd be concerned that your coils could be drawing enough to blow the 10A fuse.

[pilotyoung]

I thought I would post an update on my secondary ignition problems and want to thank those who offered suggestions. After looking carefully for a short and not finding one, I decided to trace wires from the fuse block and see where they went. When I bought the Onex I didn't get a wiring diagram, just a block diagram of which fuses were connected to what item. There were six fuses.

When I started tracing wires I found that the diagram was wrong and that the auxiliary power outlet was on the same fuse as the secondary ignition. The prior owner used a Garmin GPS on that outlet. The day my problems started, I started using a 2 port USB converter on it. The USB converter says it draws 4 amps. So with the addition of the 4 amp USB converter on that circuit it was blowing the 10 am fuse.

My solution was to add 4 more fuses (the fuse block was expandable) and I put the auxiliary power outlet on a separate 5 amp fuse. This morning I test flew it and the problem is gone.

While I am not a builder and don't have the knowledge that you builders have, I would never put anything on the circuit with the secondary ignition. I can live with losing the EFIS, the Com radio, etc, but I really want the secondary ignition to keep working.

Thanks again for those of you who offered help.

[lakespookie]

Sounds like you made a sound decision =P Glad you found out what the issue was.