Alternator? Nope--connections (I'm pretty sure)

1984 Ski Nautique 2001
Engine Model PRD WR R10
Pleasurecraft Marine
Right-Hand Rotation from Rear
351 CID -- 255 h.p.
Warner Velvet Drive Model 10-17-003
Direct Drive (1:1)


Took our new (to us) SN2001 out for a day on the lake. I noticed the voltmeter on the panel was sometimes indicating 13+ volts, and at times dropping to 10-11 volts, even above 2000 rpm (alternator should definitely be online). I've read that the wiring from the engine to the dash may be undersized and is probably a bit corroded by now, but the battery, which was very strong at first, got weaker as the day went on.

I figured, ok, I probably need a new alternator, but let's clean all the connections first. I figured this would be a great learning experience for my 14 year old son (the boat is pretty much for him and his sister). So back at home, I took out to the boat a printed copy of Tim's (TRBenj) wiring diagram:



Starting at the battery, we disconnected and cleaned every connection we could get at (nothing under the panel, that will be another day). And I do mean clean--we used a small diameter wire wheel chucked into a cordless drill. I had him clean each post, wire lug, washer and nut face. I also drilled into his head the importance of a backing wrench on the dual-nut posts, like on the alternator and starter.

We cleaned more than a dozen connections, and also unwrapped to examine a splice in the orange alternator line (turned out to be a beautiful splice job--brass crimp and solder, very nice). The alternator is a newer model with more wires, and a couple of the smaller wires disappear into the harness and apparently re-emerge a different color, so we couldn't track every single wire. But everything we could access is now clean and tight.

We put the hose to the raw water circuit and fired her up. Even ran it with a different battery from in the garage, which was more run down, so we could absolutely confirm the alternator was providing 13.5+ volts and was charging. We've been running it now and then on the driveway for other reasons, and the panel voltmeter has been steady at greater than 13 volts, once the alternator kicks in (which happens well below 1000 rpm, actually).

We'll know more when back out on the lake (which is 30 miles away), but as of now I'm comfortable that the alternator is working. All in all, a great lesson for the boy and hopefully saved me some cash. :)

Steve

Sounds like you've done a good job troubleshooting. Let us know how it charges.

This reminds me of something I'll share with you guys now :)

I worked from 2005-2009 for a company that makes fuel cells and I was the manager of training and documentation. My group wrote the manuals and trained the service technicians to commission, maintain, and troubleshoot the fuel cell systems. The system is a 12 or 24V power backup unit that automatically starts during a power outage and shuts down when power is restored. I was basically like working on a computer and a car engine, with the added bonus of high pressure hydrogen.

For day 3 of the 5-day technician training course I had the pleasure of adding bugs in the system to see if the techs could follow the manual and the electrical and mechanical drawings to trace the problem. I'd unplug a sensor, install something backwards, disable the fuel delivery or something like that. If they were stumped, the first question I would ask is "where are you in the manual?" Often the answer would be "uhhh". The point being, if they knew the symptom or got an error code, they could look it up and follow the steps to figure out what was wrong... we had every possible problem and troubleshooting step in the manual.

As you probably know, you can "out think" a problem and totally miss or ignore the easy or obvious stuff at first. When you finally go through it methodically (or by the book) and you find it, you hopefully get a better understanding of the troubleshooting method. We've all done it, whether it be fixing a computer, a car, or a Correct Craft. That drawing, and the extensive knowledge on this site are great resources for our troubleshooting.

Good for you for getting your 14-year-old thinking this way.

With this wiring diagram, does it matter if you have an internally regulated alternator? I believe my original 79SN alternator was an external regulated. Also can someone explain the function of the exciter wire off of the alternator?
I have a Prestolite distributor with EI Conversion, I'm tracing wires again and thinking it could be Overheating due to the alternator. I recently installed an internally regulated alternator.