Overcharging - 16+ Volts Merc 200 XL

[frillici]

I have a 1997 200 HP XL - carburated outboard. When you first run the engine it charges at the normal 14 volts, but when the engine warms up it jumps to 16 volts and the tachometer shows higher RPM (engine at about 3000 - but tack reads 5000). I have been told to clean the yellow wires on the rectifiers and have done that. Short of replacing the rextifiers - any ideas?

Also - how do you test and what is the cost of replacement - it looks like I have two rectifier units.

 

[Laddies]

Re: Overcharging - 16+ Volts Merc 200 XL

Yes, you have 2 rectifier/regulators. Rectifiers = $40 ea. Regulators = $135 ea. If you don't already have regulators I would change over now.

 

[hkeiner]

Re: Overcharging - 16+ Volts Merc 200 XL

I had a similar symptom on my motor. The voltmeter would show the correct voltage when the motor was cool but would jump up to about 16v when the motor warmed up. Sometimes the voltage level would randomly alternate between 16v and normal voltage when the motor was warmed up and running.

I tried doing some bench tests on the regulators (using an ohmeter and troubleshooting specs) to figure out if a voltage regulator was bad, but was never able to figure it out. I cleaned wiring connections and reapplied thermal paste to the backside of the regulatiors. Nothing helped. I couldn't confirm if my problem was the result of a thermal failure in the regulators, bad wiring connections, or bad battery. In frustration I bought two new replacement CDI voltage regulators and installed them. The motor has been charging fine ever since.

 

[frillici]

Re: Overcharging - 16+ Volts Merc 200 XL

Thanks all - and hkeiner I decided what you did and ordered two CDI regulators and will install when they come in.

They look eay to install and the cost was not too bad and purchased from IBoat.