3.0 I/O Mercruiser Not Charging

[DayCruiser]

I haven't had any problems in a long time. 1990 3.0 Mercruiser I/O 4 cylinder. So were were riding along and I notice the gauge go from 14 volts to 12 volts. So we go back to the dock and I see the blue wire to the alternator has snapped. I repaired the black or brown wire a couple of years ago when it showed it was over charging. So I put an extension wire on and plug it(got this from a auto parts store. The plug was a little bit bigger than the old one but it did go in) in as the blue wire was getting short. So we go down the lake and it is charging perfectly at 13.75. Then it goes down to 12 and then quickly back to 13.75. So we turn around and it settles on 12. I hear the engine running differently. I check the wiring at the dock and even crimp the wiring a bit more. Crank it back up and it shows a little over 10 volts. Did the blue wire snapping short the alternator? The volt meter? or was one of those about to go bad anyway? Or none of the above? I have a meter. I wiggled my wiring job and the boats volt meter didn't change. Probably can't tackle any major repairs

Thanks for any help in advance!

DC

 

[Fun Times]

Re: 3.0 I/O Mercruiser Not Charging

:welcome: to iboats, i'll be moving your thread to the proper forum and bumping it to the top for now. Good luck.

 

[bonzoscott]

Re: 3.0 I/O Mercruiser Not Charging

You can't skimp on any connections. Get some quality connectors and dielectric grease. Otherwise, I'd take the alternator out and have it tested at an Autozone or others. If it tests bad, rather than just replacing the alternator, there are auto-electric shops that supply regulator, rectifiers, and brushes - you can install easy enough. Or they can rebuild it for you. Much cheaper than a new OEM alternator. And I wouldn't put one of them $100 after market outfits in. Best stick with OEM. Electric shops - I use J&N Electric - global outfit.

 

[alldodge]

Re: 3.0 I/O Mercruiser Not Charging

Take your voltmeter and mesaure the voltage on the Orange wire with the engine off. If the volatge at the alternator orange wire matches the voltage on the battery terminal the ok. If it does not match the battery volatge need to find where the bad connection is. The black wire is ground. The red/purple stripe is hot all the time, the other purple wire is hot when the key is turned. See the attached to determine if other connections need to be redone.

 

[DayCruiser]

Re: 3.0 I/O Mercruiser Not Charging

Thanks for the input guys! I will give your suggestions a try