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Charles, Marine Mechanic
Category: Boat
Satisfied Customers: 3705
Experience:  US Navy (Ret) Certified Mercury Marine Tech with over a decade of repair experience.
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I have a 1994 25hp Mercury tiller steer that has never given

Customer Question

I have a 1994 25hp Mercury tiller steer that has never given me a problem in 15 yrs. I keep it well maintainenced but about 4 fishing trips back it started cutting out like it was running on 1 cylinder when I was going at full throttle. If I back off at low speed or just let it sit a liitle bit it goes away and runs like a top. It never dies on me when it starts acting up -I just have half power if even that. It seems to occur more on hotter days when it heats up. It only does it at med.-high throttle because I can troll around at low to idle speed all day and it never occurs. Would one of the coils be breaking down or an electronic module on that model? Doug
Submitted: 1 year ago.
Category: Boat
Expert:  Charles replied 1 year ago.

Hello, my name is***** will assist you.

The place to start is with the spark plugs. Run the engine hard and get it to cut out. Then shut it down. Remove the plugs, see if one of them is wet with water or fuel. If water, most likely place is the exhaust gasket, if fuel, the carb or the recirc system.

Customer: replied 1 year ago.
I have done all of that as I mentioned- this is an electrical problem as I explained. What do look for on this motor?
Expert:  Charles replied 1 year ago.

Use a timing light on the engine and determine which cylinder is misfiring. then you can swap the coils and see of the problem follows. If it does not, you will need a multimeter to test the output of the stator and the trigger to see if one of them may be failing or the CDI.

Customer: replied 1 year ago.
I,m waiting to get a timing lite and some help with the motor to determine the source of the problem.
Expert:  Charles replied 1 year ago.

Great,let me know.

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