Voltage Regulator Shorted and Burned up!

[Timbuktu]

Hi all,

I have an 04 F90TLRC, this weekend my voltage regulator shorted out and burned up, there was enough smoke that I got my fire extinguisher out. It was a little scary for sure.

Before I put a new one in....what causes a voltage regulator to go bad?

I just put a new battery in it. It is a dual purpose 12V starting/deep cycle battery. I have run this type of battery for a long time. My old battery stopped holding a charge, I put a newer (2yrs old but not used much) one in that I expected to work and it didn't hold a charger either.

Do you think that could have been why?

Is there anything I should check before I put it in and start it?

Thanks, Tim

[Sequoiha]

with the bad battery, with the one that wouldnt take a charge it could have over loaded the voltage regulator. in any case i have seen lots of these burn up and catch fire. they usually take out the stator, i would replace them both as a pair.

[CatCam]

Do you use wing nuts on your starting battery?

My Yamaha Mechanic told me that wing nuts on the batteries are the biggest culprit since most folks just twist them finger tight and the cable starts moving around. He said the Factory Yamaha service manuals and factory schools stress the use of lockwashers and hex nuts, NEVER wing nuts.
He expalined that when the wing nuts get loose the voltage regulator "see's" a fully charged battery, then a millisecond later a dead battery and this back and forth stuff goes on and the regulator just goes bezerk....thus the burn up.

I also have a 2004 F90 and when mine "fried" it melted the bottom of the CDI that is right above it! Parts alone ran me over $500.....you can bet your butt I have locwashers and hex nuts on my battery!!

BTW, my stator was fine.

[Timbuktu]

Thanks for the replies! Def helps to shine some light on the matter

I had nuts on the terminals at the time of the incident. I had wing nuts on the old battery, but they always stayed tight at least when I would check them.

Perhaps the VR went bad, a while ago and it just showed up now.


Thank you

[CatCam]

Mine gave me "tell tail" signs that it was on the blink before it fried. On my Multifuntion LCD gauge my voltage would be fine (13.2 - 13.8V) and later when I would look down it would be BLINKING 16.0V....it probably did this for a year or so but this is before I was "educated" on the subject of NOT using Wingnuts on my battery!!

New Regulator has been on over a year now and voltage has always been in range......

Do you have the multifunction guage on your boat and did you get the same overvoltage that I got?

When mine fried I pulling my nephews on a knee board -- I smelled something burning when I was at idle, then the engine started running real rough, I had to keep RPM's up so it wouldn't kill. I limped back to my camp. When I pulled the cowling and air cover I could see the "cooked" componenets.....It actually melted the bottom part of my CDI. I replaced the CDI as a precautionary measure as I don't want to be stranded on the water.

Interesting reading about the Yamaha/Mercury Voltage regulator problems on this link: Mercury 90-HP: Failed Rectifier-Regulator - Moderated Discussion Areas

Report back and give us status updates! Good Luck!!