Merc 70ELPT 1989 model not charging

[whopperstopper]

My dash gauge shows 11.3 volts as does both depth finders. The gauges show the same whether the engine is running or not.<br /><br />Is there any way for a novice mechanic to trouble shoot the problem.

 

[andrewkafp]

Re: Merc 70ELPT 1989 model not charging

When the motor is NOT running, put a voltmeter across the battery and set it to 12v range. It should read aroung 12.4v. Start motor and take same reading. It should be significantly higher at around 14-15v.If it stays at 12.4 or drops.. it's not charging and is likey the rectifier. Check all the connections first and then run the tests per your manual. You can easily test most of the circuits with an inexpensive multimeter.There are some good sparky's on the forums.. They will be more qualified than me.

 

[emckelvy]

Re: Merc 70ELPT 1989 model not charging

Sears has good digital VOM's and you can sometimes catch a real nice one on sale at $19.99 US.<br /><br />If you have a tach and it's not working, suspect the rectifier or rectifier/regulator assy if your has that. <br /><br />You can rule out the stator as a problem, with a resistance check. Don't have the values in front of me but I'm sure someone here does!

 

[whopperstopper]

Re: Merc 70ELPT 1989 model not charging

Yep, Tach is not working.<br /><br />Where is the rectifier and what does it look like?<br /><br />Ya'll have saved me a bunch of money in this boat restoration project and I certainly appreciate it.<br /><br />I'm good for fishing information because I have run charter boats since 1963.

 

[Exjake]

Re: Merc 70ELPT 1989 model not charging

I just replaced mine on a 1990 75 HP and its on the top of the air silencer front of the flywheel, it a easy replace.

 

[Barnacle_Bill]

Re: Merc 70ELPT 1989 model not charging

I haven't done this, but I have read several posts in various places that you can go to Radio Shack and for around $3.50 buy a 25amp rectifier. That is if you don't have the rectifier/regulator combo. I did make one for an old <br />Johnyrude once and it worked fine.