Help....Alternator...voltage regulator..battery...or something else?

[Bakes5]

Took the boat out today. It was running fine for about an hour, then it began to cut off and on when pushed. It idled fine then when I hit it, it goes good for a second or so then starts to cut out (kind of like all the electricity turns off for a second then turns back on.) I looked at the voltmeter and it was reading 10. So I limped back to the slip with it cutting off and on most of the way. When I got to the no wake zone it was idling pretty fast and making a funny noise in the engine. Couldn't tell if it was a hissing noise or bearing grind type sound. So I turn it off and then turn it back on, and the noise is gone and it idles at the right speed. I can duplicate this anytime by increasing the throttle.

My boat is a 98 2200V with the mercuiser 315HP MPI engine with about 300 hours on it


So my question is...where do you think the problem is? Does the alternator have an external voltage regulator? Could it just be my batteries won't hold a charge? Bad ground somewhere?

Anybody have an idea where to start looking?

Thanks

Bakes

[dogbert]

A couple of suggestions:

1. It could be a bad ground. I'd start with making sure the ground from the battery is properly connected to the engine block. It's possible there's some corrosion there that's preventing a good connection, so be sure to clean all your contacts.

2. The wiring harness has a major plug connector located on the front of your engine. It's sealed with some heat shrink wrap. It's possible that these contacts need to be cleaned with some sort of electrical cleaner. Be sure to get some heat shrink wrap to put around it again once you've done this.

3. Remove the battery and have it tested at Autozone or somewhere else that can test a battery. Once your boat is running, the alternator should be able to provide all of the power required to run the electronics and power the engine. However, if the battery is shorting out periodically, you'll see these kinds of strange issues.

4. Your alternator could be bad. I had to replace mine a couple of years back. On your engine, it sits pretty low and it's in the back. If you have water in your bilge, the alternator will actually begin to spray it over the back of the engine compartment...eventually it begins to corrode the alternator bushings.

[Bakes5]

The things that make me think "not a grounding issue" is that it seems to work fine until I push it. Specifically, it idles fine but then throws and electrical hissy fit when I punch it. Also, the hissy fit seems to continue until I shut it down then restart it. Also, why would the volt meter be reading 10 (it usually reads 12-14). To me that indicates the batteries are in a "discharging" condition.

Anyways, all tips or suggestions appreciated

Thanks

Bakes

[dogbert]

The things that make me think "not a grounding issue" is that it seems to work fine until I push it. Specifically, it idles fine but then throws and electrical hissy fit when I punch it. Also, the hissy fit seems to continue until I shut it down then restart it. Also, why would the volt meter be reading 10 (it usually reads 12-14). To me that indicates the batteries are in a "discharging" condition.

Anyways, all tips or suggestions appreciated

When my alternator went out, my boat ran fine until the batteries didn't have enough juice to drive the engine. I was able to recharge them and go for a couple of hours at a time. The voltage read 12 until it ran out of juice. Fortunately, I had dual batteries so I was able to keep using my boat for periods at a time over the long weekend that my alternator gave up the ghost.

You could try charging your battery overnight and see if that makes a difference. If it does, then replace the alternator. I'd also have the battery tested before replacing the alternator...its free and just takes a few minutes. If charging the battery makes no difference and the battery checks out ok, you may have a ground/short issue somewhere.

If you do decide to get a new alternator, go ahead and get the one that puts out more juice. The stock one is a 65Amp and there's another model that puts out 90 Amp. Not sure how big your stereo is or whether you plan to expand it, but, if so, might as well do it now.

[Bakes5]

Thanks....how hard is it to swap out the alternator? I'm pretty good mechanically but it looks a little tucked away

thanks

Bakes

[dogbert]

You'll need a belt tensioning tool for the serpentine belt, but other than that it's pretty straight forward. It does require some gymnastics because on a V-Drive, the engine is in backwards, so the alternator is on the starboard side in the back, kinda low on the engine.

[Bakes5]

sweet...thanks...anybody got a source for a 90 Amp alternator? Preferably something I can just order and then have it show up on my doorstep.

[dogbert]

Here's a link. There's a sticky thread on the Maintenance and Care forum with the same info.

[Bakes5]

All fixed....replaced both batteries (they were both 5yrs old and one was completely dead) and the alternator (haven't tested it yet but I am guessing it is going to be bad)

Thanks for the advice.

BTW....swapping out the alternator was a piece of cake

Later

Bakes