Electrical issues OMC

BlueDart

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Oct 27, 2015
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I have two questions and I'm sure to you that are reading they are very simple.
Do note I'm a retired accountant and we are not know to be mechanical people.

My boat is a 1985 Doral bow rider with a 3 L OMC Stringer engine.
Please no negative comments on my Stringer as she is sensitive.

I've been told that leaving my ignition switch on can overheat the electronics and therefore hesitate to track the wires I need to connect depth finder to the ignition. The only way to test for proper positive and negative is with my tester but need ignition on to do so.
Is there a risk of damaging electronics with ignition on and if so how much time do I have for my testing.
The positive is obvious but not so to me is a ground.

Secondly I need to replace my alternator and even to me, a non mechanical person it looks very straightforward.
That being the case would order an alternator on line and install myself.
I have been advised by the online supplier of what alternator should be a match but not sure of it fitting the existing bracket on the engine.
Is there a fool proof way of ensuring a match to avoid ordering mistake.

Thanks
 

Bondo

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Ayuh,.... Ya probably should hook up the fish finder to a circuit other than the ignition circuit, an accessory circuit, independent of the ignition,.....

There should be other power sourses available under the dash,...

If ya shop by serial numbers, ya usually get the Right part,....
Other than that, pictures of the replacement, 'n matchin' that to what ya got,....

Mountin' is fairly standard, wirin' varies alot,...
 

alldodge

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Not an OMC expert but I do believe the purple wire is switched by the ignition switch.

As for the ALT shows us yours and we can figure it out for ya
 

BlueDart

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Not sure I know what is meant by "switched by the ignition switch" ... is that some reference to it being positive or ground wire??
 

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alldodge

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Not sure I know what is meant by "switched by the ignition switch" ... is that some reference to it being positive or ground wire??

I think that ALT has been replaced prior. I have one sitting on the shelf which was a one wire, then used the plug and added it to the back to make it work like a regular marine ALT.

The switch is, turn the key from OFF to ON and the key "switch" applies 12V power to the purple wire which applies power to everything the motor needs. So if you connect the depth finder to the purple wire it should turn ON when the key is turned
 

BlueDart

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If that is true that what I am trying to match is a replacement does that not lead to error in choice at this time.

Thanks to all for the information and the purple wire is the one I want along with then a suitable ground wire.
 

alldodge

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Replacing the ALT with the same type should not be an issue so long as it is marine rated. That said are you sure the ALT isn't working?
 

southkogs

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OMC part# for that alternator is 0983424 - NAPA stores may be able to help you cross reference.
 

BlueDart

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Thanks to both of you for the assist and will trailer start the boat and test alternator before ordering replacement.
Had planned on starting it that way before my first splash in the bay to ensure all is well.
 

southkogs

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Might see if you can have that one rebuilt before buying a new one (assuming it's a marine alternator).
 

BlueDart

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With some hesitation in belaboring this issue another point is the installation as most alternators I see which are claimed to be compatible have a 2 inch mount.
The existing one is slightly over 3 inches which my research tells me is a probably saddle or dual mount alternator.
Does this make any sense and if so how do I find that type of alternator?
 

southkogs

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I'm not sure about the difference in the mounts, but yours looks like the Delco style that OMC used. The mount bracket (#0910342) for that should still be available, as should be the brace (#0910344). The screw for the bracket is still available too, but I don't know how long it is.
 

BlueDart

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Thanks southkogs because it seems the majority by a long shot are 2 inch foot whereas the current bracket is in the 3 inch range. I either need a different bracket to take a 2 inch foot or spacers to take up the excess with the existing.
 
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