Verifying Regulator/Charging System on Merc 90, 4 Stroke

[Stamey]

I have a 2001 merc 90, 4 stroke in which the voltage regulator caught fire, burning up several pieces under the hood including the CDI module. 1400 bucks later I have reassembling the engine and fired it up. It runs fine on muffs and is putting out 14.72v to the battery at idle. Service manual says that I should have no more than 14.5 to 15.0 volts being output from the charging system. What worries me is the voltage regulator was getting pretty warm after only a couple of minutes of run time. I realize that the regulator is equipped with fins for this reason but I wonder if the voltage regulator is being overworked and, even though this is the latest revision of regulator design, if the stator is putting too much out. Perhaps this is why the previous regulator caught fire?
I am just trying to make sure I have checked everything I can to prevent another fire from occurring, not to mention the crazy cost of the parts.


Thanks,
Chris

 

[carholme]

Re: Verifying Regulator/Charging System on Merc 90, 4 Stroke

What is your engine s/n?

Have you done the amps check per 2B-8 of the manual?

Gerry

 

[Stamey]

Re: Verifying Regulator/Charging System on Merc 90, 4 Stroke

Engine SN is 0T318029
I have not done the amperage test as I do not have an ammeter that can handle 20+ amps. My multimeter will only do a max of 10 amps.

Thanks,
Chris

 

[Stamey]

Re: Verifying Regulator/Charging System on Merc 90, 4 Stroke

So I have purchased a cheap clamp-on ammeter that will handle lots of amperage, so I can check that tomorrow, as I am heading up that way. The boat owner has done some checking on it and tells me that her voltmeter in the dash is reading 18+ volts with the engine running, although a voltmeter on the battery at the same time says it's 12v. The next thing I need to figure out is if the voltmeter is bad or if something from the engine, and the new voltage regulator is causing the voltmeter to read incorrectly. I ask this because on my 70 Force, when the regulator went bad, the tach stopped working, which taught me not to rule anything out and ask if I don't know.
Is there anything in the electrical system of this Merc that will cause the onboard voltmeter to read incorrectly?

Thanks,
Chris

 

[oldman570]

Re: Verifying Regulator/Charging System on Merc 90, 4 Stroke

A load test of the battery might be worth a try to see if the battery has any troubles. Only wet cell maintained batteries should be use on a marine setup, as maintance free batteries are not recommended. A check of all the wire connections to be sure that they are good and clean. A check at the CDI website will get you more info as how to test and repair most all electrical problems. Moat tacks pickup up a signal from the regulator/ rectifier on the motor, and this is why the tack dose not work when the rectifier goes bad. JMO
Oldman570

 

[Stamey]

Re: Verifying Regulator/Charging System on Merc 90, 4 Stroke

OK, went out and checked it again, At idle or 3000 RPM, it measures 14.9V and 2.4A, after it has run a few minutes to charge the battery back up after the drain from starting. Right after start it was charging at 14.6V and 3.4-4A.
Seems like it's OK to me.

Thanks,
Chris

 

[woody66912]

Re: Verifying Regulator/Charging System on Merc 90, 4 Stroke

OK, went out and checked it again, At idle or 3000 RPM, it measures 14.9V and 2.4A, after it has run a few minutes to charge the battery back up after the drain from starting. Right after start it was charging at 14.6V and 3.4-4A.
Seems like it's OK to me.

Thanks,
Chris

Make sure you remove the paint from the mounting bosses, or any other ground locations. Your numbers look good.

On a side note. I have been replacing these for over 20 years now, Come on merc get it together!!!!!!!!!.