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2001 Mercury 90HP Electrical Fire

J

jlbost3

New member
My brother in law took my boat out last weekend and said the engine started smoking and smelled like burnt plastic. Towed it home and took the cover off, sure enough the cdi box, wiring harness, and regulator/rectifier were all melted and burnt up. Previously the motor had a charging problem where it would not charge the battery. I remedied this by installing a 100w solar panel connected directly to the battery. Based on my research there is a good chance that it was the faulty regulator/rectifier that caused this issue. I spent $700 on new parts to replace the CDI, harness and regulator/rectifier. My fear is that I will install these parts and crank the motor up and it will happen again. Does anyone have experience with this issue? Should I go ahead and replace the stator as well? The exact model number of the motor is 90ELPT. It is a carbureted 4 stroke.
 
The early regulators on the 4 strokes did indeed burn up.
There was some type of service bulletin or recall (I can't recall specifics) about 2005.
 
Your failure to fix the charging system problem when you should have contributed in part to the problem. The regulator sits right under the CDI box. The regulator catching on fire takes out the CDI box.

Usually poor electrical connections cause the problem to begin with. Corrosion causes poor electrical connectivity (high resistance) which then translates to excessive temperature. Given enough time flames happen.

The stator itself may or may not be damaged. More than likely the electrical connection from the stator to the regulator is damaged.
 
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