40 hp 2cyc Mercury not charging

Hello all. I'm working on a friends pontoon that has a 40 hp Mercury that isn't charging. The serial and model numbers are below. I was hoping the problem was the fuse in the holder attached to the motor but it wasn't. While trying to get the regulator off I noticed two wire connectors that I believe come from the stator that were melted together.

I'm trying to decide where to start on diagnosing the issue. The book I have doesn't cover testing the regulator or stator. Could any of you point me to test procedures for them? I couldn't really tell if the two wires actually shorted together, but it doesn't look good.

Thanks,

-Ethan

serial number 0t475111
model number 2002 40elpt0

After a bit of searching, It appears that my book does have a stator and rec / reg testing procedure. I'll get back to the boat this week, check it, and report back.

-Ethan

Are the procedures the same for larger motor? What size engines does your book cover?
I have a 75 H.P Mercury Mariner, & it isn't charging either.
not sure if there are loose connections at battery, or something at the engine.

I would think they would be similar but I can't say for sure. The book I used was a Clymer manual that covers 2.5 to 60 HP 1998 - 2002.

In my case the resistance between the two ac lines from the stator were supposed to measure between .16 and .18 ohms. I was getting consistent measurements of .2 ohms. I think it's pretty hard to measure resistance that low with a typical multimeter. The values were less than the margin of error for my meter so I decided it was close enough. I replaced the ends of the two ac wires from the stator as they were a bit melted. The measurements for the rectifier/regulator were way off. There were a couple of tests that should have resulted in around 600 ohms that were reading mega ohms. I decided that the rectifier/regulator was probably the culprit. I replaced it with a $30 aftermarket part and it's now working well (although it only has a few hours or run time on it). The initial thing that made me think the issue was the rectifier/regulator was that the tach was not working. It's is what provides the tach signal on the motor I was working on.

Good luck with your 75 HP Merc.

-Ethan

I tested my rectifier and found it wasn't working properly either. Now getting 15.2 volts at the rectifier output at idle. Hope it doesn't overcharge the battery. not sure what amps it would put out from the stator charging system. I didn't realize stator put out AC voltage until doing some reading and watching you tube videos.