Mercruiser 5.7 - voltage questions

[ourobos]

Hi guys, I have a 1989 Rinker Captiva 206 with a Mercruiser 5.7 (350). Took it out the first time, and the batteries weren't charging. After pulling the alternator, I discovered the power wire from the alternator to the batteries was broke at the eyelet. Replaced it. Now when running with muffs, I only get 12v at each battery, tested via my DVOM. Is there anything else I can check before I pull this alternator again and go have it tested, as it has two wires that would have to be cut, they're crimped, looks factory. Only two wires besides the power wire. Any help is appreciated.

Thanks
Brandon

 

[bobzak]

Re: Mercruiser 5.7 - voltage questions

put your meter directly on the post behind the alternator and see what you have there. if it is higher than reading at battery than you still have a wire or crimp issue. try bumping up your idle a few hundred rpm's and see if the alternator picks up. some alternators will not start putting out until rpm's are greater then 800 to 850 rpm.

 

[Don S]

Re: Mercruiser 5.7 - voltage questions

Read this bulletin on testing your alternator.

 

[KD4UPL]

Re: Mercruiser 5.7 - voltage questions

I have to run my RPM's above about 1,500 before the alternator will start producing current. After it does, I can throttle back down to idle and it will continue to charge.