Coil Issues any thoughts?

[JINXBASS]

Serial # 1b916908 Mercury 250 proxs approx. 600 hrs original powerhead 2012

I had a coil go bad on me last year. No big deal put one on it and ordered a spare and just about a month ago I burnt another coil (not the same cylinder). So I replaced it with my spare and ordered another one. Well yesterday I burnt another coil. Once again it was one of the original coils not the newer replacements. So this brings up a question of are all of them going to start going out? I heard of some problems with some coils a few years back does mine fall in these bad coil years? At $150 a pop this is getting expensive. Any advice or ideas?

To Don I just got my replacement for the last one in a couple days ago. So I guess I will contacting you to get another. Good thing is I had one on hand.

Thnaks

[Macsimus]

NOT saying this is your problem, but I had multiple coils fail this summer before I found a wire in the ignition coil circuit that was grounding against a bracket. http://www.bbcboards.net/showthread.php?t=999306

[EuropeanAM]

I would definitely be inspecting the coil harness and connectors for any signs of damage or problems.

[JINXBASS]

I would definitely be inspecting the coil harness and connectors for any signs of damage or problems.

I will definitely look into that.

[JINXBASS]

Ok guys I went over the entire coil harness and found no problems. I did find the wires going to the alternator was rubbing bad. It has not quite went through the insulation. So I took care of that and put a new coil on it.

Any other ideas?

[EuropeanAM]

Off the wall question: Have you had a few instances where you are cranking the engine, it doesn't fire off and you remember and flip the lanyard switch back "on" while still cranking?

[JINXBASS]

Off the wall question: Have you had a few instances where you are cranking the engine, it doesn't fire off and you remember and flip the lanyard switch back "on" while still cranking?

I do t think I have ever kept cranking while flipping the lanyard switch. But I very often go to crank the motor and the lanyard is in the off position because I wear it Everytime on plane.

[JINXBASS]

Another tidbit of info. The last coil went out while idling towards the end of the day. Do t know if that information changes anything but just a FYI.

[EuropeanAM]

I do t think I have ever kept cranking while flipping the lanyard switch. But I very often go to crank the motor and the lanyard is in the off position because I wear it Everytime on plane.

This, or excessive-length periods of cranking are about the only other item we see causing repeat electrical failures like this (at least in engines of this vintage... earlier coil versions are a whole different story).

[lpugh]

I think it would be wise to verify the correct plugs set at the proper gap would be in order as well as checking the resistance in all the plug wires. In the automotive field I have seen hundreds of coil failures due to high secondary resistance as it will cause the coils to operate at near maximum voltage output constantly breaking down the insulation in the coil or causing the windings to short circuit. I have also seen loose spark plugs cause this as well. A plug that is loose will not dissipate heat as well and cause the plug to run way to hot, sometimes even melting the electrodes off.....proper torque is critical