200 hp BLACK MAX missing at planning speed when wharmed up only.

My 200 hp. Black Max runs fine when idolling, take off, and when planned out but after running for about 5 miles while planed out at lake powell when it wharms up it misses really bad, but still stays at plane but at a lower speed??. Is one of the six coils bad or switch box? or something else that i dont know!?

Re: 200 hp BLACK MAX missing at planning speed when wharmed up only.

It is certainly easier to test the coils. The switch box cannot be bench tested and requires a DVA meeter. You have to troubleshoot the individual wires on the trigger, stator, and coil leads to determine if they are bad or consequently the switch boxes. I recently had an issue with no fire and it led to total frustration and I took it in and had a crank test and it turned out to be the trigger and stator not the switch box. It was worth the $60. If you end up replacing one you might consider replacing them both unless you can find an exact match.

shane

Re: 200 hp BLACK MAX missing at planning speed when wharmed up only.

The last i knew if the switch box goes bad you dont get any spark at all, but as soon as the engine warms up at normal temp it misses, and if you put it newtral and rev it up it still runs good. So i am wondering what it is that that when warm is making it miss when its planned out at about 28 mils per hour? To me it seems that what ever it is that advances and retards the timming could be the problem but im unsure. It has three carbs and is a v six with 6 independent coils going to each sparkplug.

Re: 200 hp BLACK MAX missing at planning speed when wharmed up only.

maybe it could be the ignition stabelizer aka black box that sits on top of the head. Try taking it off. It can be replaced but its not worth the money since you dont need it. there is a few threads about the stablilizer in here somewhere. perhaps the switch box could be getting hot and not working properly, but they usually sit slightly away from the head.

Re: 200 hp BLACK MAX missing at planning speed when wharmed up only.

I just read elsewhere where laddie wrote that a bad rectifire can cause the stator to overheats and misfire.

Re: 200 hp BLACK MAX missing at planning speed when wharmed up only.

Black Max runs fine when idolling, take off, and when planned out but after running for about 5 miles while planed out at lake powell when it wharms up it misses really bad, but still stays at plane but at a lower speed??.

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I suggest a systematic troubleshooting approach by first confirming that the miss is due to a weak or failing spark and if so, which cylinder(s) has the bad spark. After you detemine that, you can switch some parts around to see if the bad spark moves with the part or stays with the cylinder. This troubleshoot step would provide some pretty good info on diagnosing the likely problem. The thing about ignitions systems is that many of the parts are expensive and replacing them on only a hunch can make the process expensive and frustrating. Even more so when the problem only occurs at high engine speed and checking the ignition at idle on muffs does not show any problems.

I have previously used a SmartTach meter to directly measure the secondary voltage in the spark plug wires while the motor is missing at high speed out on the water. It is a quick way to confirm spark weakness and/or failure under these conditions. Once a spark weakness/failure is confirmed, a DVA meter and/or swapping some parts are a usefull way to narrow down the probable cause. Just my thoughts...

http://dolphinmarineservice.homestead.com/ign5.html

Re: 200 hp BLACK MAX missing at planning speed when wharmed up only.

Thanks for the info, after checking everything out it turned out to be the stator.

Re: 200 hp BLACK MAX missing at planning speed when wharmed up only.

after checking everything out

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Can I ask what you checked and how you checked it to determine that it was the stator? I am always interested in identifying the most successful troubleshooting approaches when it comes to ignition related problems.