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I have a 1999 130 that keeps fouling the plug (dry black tip, dark brown/black on insulator)on my #2 cylinder (top, port) and to a much lesser degree #4 (bottom, port). The starboard bank plugs look perfect. Compression is perfect on all 4 (so rings/piston should be good), timing is fine, carbs cleaned and adjusted, yet still having the problem. Could my CDI be causing this? I still think it is an ignition problem but can't put my finger on it. I tried switching the coils/wires and had the same prob. in same spot. Any other suggestions before I drop money on a new CDI?
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Snooker,
I was hoping someone could give you a more definitive answer by now, so I will go ahead and give you my 2 cents worth.
Sounds like you have it isolated down to ignition problem, but I'm thinking maybe bad reed valves could cause this?
CDIs are expensive, especially if you don't know for sure if that is the problem. I'm not real familiar with the pulser coils of the stator, but I believe that is where the timing comes from to fire any particular plug. I'm hoping another forum member will give us his thoughts on this.
If you do want to try another CDI, might take a look at ebay.com - I see them up for auction from time to time - might save you a few bucks.
Good luck,
Ken KComment
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Thanks Ken, I had thought about the reed valves so I pulled the breather and ran the motor at various speeds with a mirror in front of the carbs. I didn't get any fuel spitting out of the carbs, so I ruled out the reed valves. Correct me if I am wrong, but I thought that if you had bad/cracked reed valves you would get fuel spitting out of the carbs? Let me know if I am wrong as I am not eager to pull the intake manifold just to check the reed valves. This weekend I'll change out the fuel pump and see if that makes a difference. At least that is easy and quick and one thing I can rule out.Comment
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Snooker,
I am impressed with your test on the reed valves - truthfully, I have never had to check them on an outboard, but what you did is exactly what I would look for. I have seen bad reed valves on smaller engines, and yes, fuel/air mixture will blow back out of the carb throat.
If that fuel pump replacement doesn't help, then its time to look at ignition.
Let us know what you find out.
Good luck,
Ken KComment
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