Alternator issue?

aero3113

I noticed last night while under power with my nav lights on the volt meter was at 12 volts (usually just above 13V). I slowed down and put the boat in neutral and revved the engine and it stayed at 12V. When I got to my dock I turned the nav lights off and saw the meter slowly go up to 13v I then revved the engine and the meter went down to 12V. What do you guys think? Also can a bad alternator give you a power loss? I could only get up to about 4200 RPM's at WOT when it should be 4600?

Dream_Inn

Definitely sounds like a regulator. I'd say your best bet is to remove the alternator and go to an automotive shop for testing.

aero3113

I was going through my maintenance records from the previous owner and didn't see anything for an alternator. I'm thinking I might just go ahead and replace it for preventative maintenance and then trouble shoot from there if it doesn't fix the issue.

aero3113

RinkerYan said:

I bought a new one and had the old one rebuilt for a spare. It was like $60 to rebuild with new brushes, bearings, regulator, etc.

Sounds like a good plan!

aero3113

I replaced the alternator today and still have the same issue. I turned on the nav lights and put a meter on the batteries with the engine running and they read 13.8 volts in all positions of the battery switch and the gauge on the dash read 10-12 volts. Do you think it's a faulty gauge? I also had a strange issue today when I went out to test run the boat. At WOT which was still 4000-4200 I played with the trim tabs and the engine would start to bog down when I would push the buttons?  Once I got back to the dock I opened the hatch to look things over and heard a couple of drips of water. I think my bellows are leaking! I'm dropping her off at the marina tomorrow to have everything looked at.

Michael T

The trim tabs do draw some serious amperage. There is also the possibility of a short to ground that is siphoning off amperage. The marina can easily check both the trim ram draw and voltage gauge. MT

aero3113

I just dropped of the boat this morning and they are saying that my batteries are most likely going bad and not putting out enough amperage. That's why my volt meter is jumping when a load is put on ( I hope). Not sure if that will cure my RPM issue but will let you guys know what they find with that.

Black_Diamond

A load test will tell if it is the batteries, many a battery shows 'good' voltage and fails at delivering current.  This would mess up your engine computer too (low voltage/amperage), so hopefully an easy fix.  Good luck!

Michael T

Is this the time to go AGM series 31s? MT

aero3113

Black_Diamond said:

A load test will tell if it is the batteries, many a battery shows 'good' voltage and fails at delivering current.  This would mess up your engine computer too (low voltage/amperage), so hopefully an easy fix.  Good luck!

BD, I tested the batteries with a meter last night with the nav lights on and they did read 13.8, I hope they are the issue.

MT, would be nice to get AGM Series 31's but have to see what this maintenance bill is going to be 

aero3113

I got the boat back this morning! The electrical issue were some connections at the starter that needed to be replaced. The RPM issue was that my exhaust flappers broke off and were restricting the exhaust!!!! Its a good thing that my bellows needed to be replaced or I wonder if they would've found them! What I find strange is that my exhaust flappers were just installed new last season.

Dream_Inn

Wow! two different issues! Glad both were found, and that is strange that flappers were just changed out.

aero3113

I forgot to add while they were replacing the bellows they also changed the shift cable and replaced the gamble bearing (it was a kit that included all) they also got my trim gauge working!

Black_Diamond

Good deal. The trim gage is a picky item on the drive to mess with. Enjoy!

MarkB

What did they do to get the trim gauge to work. Mine doesn't get all the way to 0 and when I turn off the engine it shoots all the way up to trailer position. 

aero3113

They replaced the sending unit. They said since the bellows are going to be replaced now's the time to change it.