On May 21, 7:17*am, tem wrote:
I have 1986 Mercruiser 170 (mdl MCM 170) w/ 2 battery system. This may
be a dumb question, I'm not a mechanic. My volt meter reads 12.3 on each
battery when engine is not running and 12.2 after I started it. Does
this mean my charging system is not working? Any help or advice is
appreciated.

--
tem

Did you take a direct reading off of the Alternator while engine is
running? Thats where I'd start.