www.iFourWinns.com

So, I imagine my alternator is going, going and/or gone. It is pretty hot to the touch and I really don't think the batteries are getting charged. If I cut the engine off and swim for a while and go to start it, lights dim, radio turns off etc...and it BARELY starts. SO...I am fairly certain the alt. is shot.

I believe is a Delco style alt (1987 4.3 OMC), what amp or alt should I look at getting...would 55 amp suffice or should I look at the 78? Where is the best place to order one from? Thank you!

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1987 Sundowner 195, 4.3 OMC " Z boat"
1983 Wellcraft 248 Sportsman, 3.0L OMC Sea Drive "Born Again"
9' Patriot 40lbs TM "Quack Addict"

That's not a difficult one to test. Get a volt meter(not expensive) and check you battery voltage with the engine off. Should be about 12.6 volts on a new fully charged battery as long as it hasn't been recently charged in the last 12-24 hours. Just coming off a charger the battery will retain a higher voltage.
Careful! while the engine is running check the battery again. It should be just over 14 volts. There will be a noticeable difference when your engine is on.

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--2002 3880 Regal Flybridge | Twin Merc 8.1HO **Seven**
--2003 AB 13 VST Console Inflatable | Tohatsu 40hp TLDI **Phish'n ski**
--310 Mercury Inflatable | 1982 9.9 Johnson

i would just pull it and take it to a local auto parts store and have it checked out , need to have it load tested

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1989 245 vista
5.7 cobra

That's exactly what I had in mind. One of the things I've had an issue with is a surging idle.... If it stays running but mostly it fires up then immediately dies. I'm thinking on top of the voltage issue, I've got a stuck anti siphon valve

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1987 Sundowner 195, 4.3 OMC " Z boat"
1983 Wellcraft 248 Sportsman, 3.0L OMC Sea Drive "Born Again"
9' Patriot 40lbs TM "Quack Addict"

Yeah I've done that.... No significant change in battery voltage with engine running. Stays just under 13v . both batteries are fresh marine batteries and I think engine problems at high RPM stem from voltage loss at battery. This is when the engine would reach high rpm. Now I thinking there's a fuel starvation issue. After all the sea foam I've put through it it wouldn't surprise me if everything is crudded up

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1987 Sundowner 195, 4.3 OMC " Z boat"
1983 Wellcraft 248 Sportsman, 3.0L OMC Sea Drive "Born Again"
9' Patriot 40lbs TM "Quack Addict"

I went thru this in the spring of 2013. New alts are expensive because they are marine rated (spark proof). Like $200-$300 worth! I took it to a parts store and they were unable to test it, because of the type of connections it has. I did call a local marine mechanic and he said he would have it rebuilt. And suggested a place and they tested it there and it cost like $80 for a rebuild with a 1 year warranty. I have the same motor you do but mine is a '90. Check to see if it can be rebuilt before you go out and spend a fortune on a new one.

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1990 Four Winns Horizon 200
2005 GMC Sierra

+1 on getting rebuilt. Also, if you say it stays at about 13 volts even at idle then it sounds shot to me.

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--2002 3880 Regal Flybridge | Twin Merc 8.1HO **Seven**
--2003 AB 13 VST Console Inflatable | Tohatsu 40hp TLDI **Phish'n ski**
--310 Mercury Inflatable | 1982 9.9 Johnson

Yeah that's what I was thinking. Getting it rebuilt because shopping around I have noticed that a new Delco style marine alt is at least 160 (amazon). If I can get mine rebuilt for half that....

Yeah it is hovering just below 13 (basically the voltage of a good battery) and when I flip anything on, or tilt trim it drops to just over 10 then comes back up to almost 13v. So I know the batteries are good. That, and the alternator gets really hot (too hot to touch) while running I think at least one diode is gone if not an internal short.

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1987 Sundowner 195, 4.3 OMC " Z boat"
1983 Wellcraft 248 Sportsman, 3.0L OMC Sea Drive "Born Again"
9' Patriot 40lbs TM "Quack Addict"

Take it to a place and have it rebuilt they tested mine for free and gave me a quote on the spot. Much cheaper and worked like a charm! Plus if you have it tested and its good then you know it is something else that is the issue, before throwing good money after bad.

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1990 Four Winns Horizon 200
2005 GMC Sierra

Am going to remove it from the boat tonight and bring it to a shop tomorrow. I've taken stuff to this shop before and their good

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1987 Sundowner 195, 4.3 OMC " Z boat"
1983 Wellcraft 248 Sportsman, 3.0L OMC Sea Drive "Born Again"
9' Patriot 40lbs TM "Quack Addict"