Merc 200 Electrical Problem

Hi Randy, 

I have a 1993 Mercury 200, carbureted, and have been running into some weird problems.  The motor starts up and runs fine on the trailer but in the water it will run fine for the first few minutes but after it warms up, at idle, it bogs down and acts like it vapor locks. After twenty or so minutes, it will start again and run for awhile.  I had the carbs checked and adjusted and the tech, who was highly recommended by two different, unrelated charter captains and one other friend of mine, said they were very clean and just needed adjustment.  He did the recommended adjustments, same problem.  At the same time, I can run the boat and I seem to lose power at the top end and at idle after running it for awhile.  The batteries are also not charging properly.  Changed a voltage regulator that had burned, same problems. Changed an oxidized (slightly) switch plate (broke off a stud cleaning it with a brush), same problem. Both batteries will discharge during a day of fishing or trolling and by the time I return to the dock, they are mostly dead. I ran the boat on the trailer tonight and noticed that the batteries, while the gauge said 14 volts, do not consistently maintain the lights at idle. They would fluctuate in brightness. The batteries are also new. 

I have owned this motor for 7 years now and have maintained it meticulously.  Until this year I have not had any failures of any kind.  This year, my towing insurance is getting a workout.  My question is this.  I have replaced a switch box, a voltage regulator, much of the battery wiring, the batteries, etc.  I have been advised that my stator or trigger might be bad but I hate to spend the money replacing it for nothing. Any ideas?  Would a bad stator cause the stalling problem too or is that unrelated? 


Chris Sizemore - Bonita Springs, FL



Sounds like the low speed side of the stator is breaking down. Mercury stators are not the greatest and fail quite often. Try this item first, as you have done pretty much everything else already. 




Please submit whatever questions you have to  All questions and answers selected will be displayed on this page as they come in.  Note: though all boaters are welcome, priority may be given to I.H.R. members.  Randy can not be held responsible for any advice given.  Though his information and expertise is second to none, he has no control over what you do with your boat.  It is up to you to boat safely and act responsibly, and his advice is only to be used as a guidance for your high performance boat/motor of which you are the one responsible for the risks involved.

Mark C.


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