'78 1150 2-Stroke Wire Corrosion

spitfireap

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Oct 22, 2016
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I own a '78 115 Tower of Power that's my first boat engine on my first boat (owned about 3 months). I've been doing a decent amount of reading to learn how to care for this thing. I was in the process of winterizing it (pretty easy) when i noticed that some of the wiring had missing/deteriorated insulation and the wiring was corroding. I don't know how I didn't notice until now as it's so obvious. The boat's been on the water about half a dozen times this summer with no issues other than the typical difficulties with cold starting (just figured out how to overcome that today - practically flood it with the primer bulb, choke for 10 seconds, and POW...started in 2 seconds).

My question is where the best place to get a replacement wire harness to fix this mess during the winter? Also, a wire leading up towards the flywheel is also corroded. Will I have to remove the flywheel to replace that? I'm still figuring all the parts in this engine, so I'm not sure what that wire is for (pic#2). (Pics are at the link below to my Onedrive folder - I couldn't upload them here for some reason). Thanks in advance for the help.

https://1drv.ms/f/s!Av8_LOjr0nXx8njhuglw1RLuBOYe
 

GA_Boater

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49,038
Welcome aboard.

A common problem on older outboards and Mercs seem to be the worst. This the CDI replacement for your Wiring Harness - http://www.iboats.com/Mercury-Marine...view_id.335997


The 2 wires in pic #2 may be repairable. You need look under the insulating tubing. Too early to tell if the flywheel needs to come off.
 

Chris1956

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Mar 25, 2004
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27,033
The stator can be removed after removing the outer flywheel. It is held on by 6 or 8 bolts centered around the large flywheel nut. Check the surplusunlimited web site for that wiring harness.
 

Watermann

Starmada Splash of the Year 2014
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Jan 12, 2013
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One thing you shouldn't do is make butt splice connections in the harness. I really don't know if anyone makes a direct replacement motor harness.

Amazing these motors run so well with crossed wires and corroded connections.

Pic%202.jpg
 

merc850

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Jul 7, 2010
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I would take care of that alternator wiring - there is a lot of current passing thru those wires; I strip the wire to find a good part then solder a new wire to it - if you are going to unbolt the flywheel mark it in relation to the hub; when you put it together use 20 ft/lbs of tork and Loctite. CDI probably sells the wiring harness and it's worth the money to have it safe and fire free!
 

gm280

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Jun 26, 2011
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If you can't find the wiring harness as a whole, then you will have to purchase the wire in each color and make your own. But use the exact same colored wires that are on the original harness and make sure you buy marine grade wire as well. Marine grade is tinned and will withstand a lot more corrosion resistance properties then you presently have. And I know that sounds impossible to manufacture your own. But if you take each wire one at a time and make a replacement one, it goes pretty easily. Just don't cut corners making any replacement wires. Use quality components and you will enjoy your engine for many years to come.JMHO
 

Watermann

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The pic they show is for the boat side harness with the plug but GA is right that actually is the internal engine harness. :thumb:

If those 2 are the only wires in the harness that are bad then you could just replace them.

Butt splices on TB ignition wiring can cause you to loose some very expensive parts due to the resistance they create.
 

GA_Boater

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The pic is the internal harness. The pins are male and the boatside is female. From the parts diagram, the CDI and OEM internal harnesses have the big connector, just like my internal harness. Also the boatside harness is 20 feet long. Don't want spitfire to be confused. :smile: harness1.PNG
Internal harness;



4142770_1.jpg


Boatside harness;
t.png


t.png
4749550_1.jpg
 
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