Not charging
 

My 150 1988 mercuty out board is not charging the batteru ., it only puts out 12.5 volts ,it used to put out 13.8 volts. Is there a way i can check the rectifier to see if its workinh thanks

set meter to resistance or continuity and touch any two terminals and then reverse leads on the same terminals... one way should be open circuit and the other should be closed.... repeat test on the other two terminals

I doubt it charged a full 13.5. the charging systems weren't that strong. Does your tach work? Usually if the tach is working then the charging system is working. Put a volt meter on the battery, check it with the engine off, then crank it up and check it again, then rev it up to 1500-1800 and check again

I did the change was minimal motor not running 14.4 volts. ,,,motor running at high idle the same no change

Sorry its 12.4 volts not 14.4 sorry for the mistake thats what happens when you use a tablet

how would i check the voltage regulator to see if thats working. i replaced it about 6 years ago for about 50 dollars but the same part today is 200 dollares so i want to make sure thats the problem before i start changing parts

need to find an actual mercury shop manual for your particular motor. clymer, seloc, etc are no good. they will tell you exactly what to test and what to replace. might pm bigshrimpin, i think he used to have some older shop manuals.

cdi electronics will have a complete step by step breakdown to check it. check their website