1970 Mercruiser 165 l6 Charging problem.

wmrowe3

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I have an old 19.5 ft with a merc 165. The wiring is a mess. Many hack jobs. In the proccess of fixing. I cannot find a good diagram and need some help figuring out the starting and charging system. Any help would be appreciated. Thanks
 

ziggy

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Jun 30, 2004
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Re: 1970 Mercruiser 165 l6 Charging problem.

what ya need is the oem service manual. it has the wiring dia. in it. check this out....
 

wmrowe3

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Re: 1970 Mercruiser 165 l6 Charging problem.

Link didnt work. My question has to do with the positve side of the coil. Wire from switch has been changed and there was a resistor inline between coil and wire. the resistor nocks the voltage down to 4 volts and no spark. When I removed the resistor the coil boils. Lost
 

fishrdan

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Jan 25, 2008
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Re: 1970 Mercruiser 165 l6 Charging problem.

Ziggy's link worked for me, you have to click download, wait............... then download.

The coil's voltage should be around 9V, if it's 4V the resistor wire or resistor is bad, or you have a loose connection somewhere.
 

Fishermark

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Oct 19, 2003
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Re: 1970 Mercruiser 165 l6 Charging problem.

Here ya go:

mercruiser165wiringdiagram-2.jpg
 

wmrowe3

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Re: 1970 Mercruiser 165 l6 Charging problem.

Thanks for the advice. I was able to download and was very happy. Now the only thing left is figuring out the charging. I cant find a voltage regulator so am hoping its built in to the altenator. the coil thing still may be an issue. But with your advice and the manual I will get it done.
 
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