1979 140 Merc not charging?

dgsmooth

Cadet
Joined
Jul 1, 2011
Messages
11
howdy all - i have a 1979 (i'm pretty sure) merc 140. took it out for first time of season, ran good, but i shut it off in the middle of the lake and when attempted to re-start battery was next to dead....i thought. it simply will not turn ove. starter clicks and engages but not even one rotation. so i pull started it with the emergency rope and got it running, and ran good again, but no crank when shut-off again. i'm guessing by that the stator is working or it wouldn't run, rectifier failed? i pulled the battery out tonite and will test at work tomorrow (i'm a heavy duty mechanic) to make sure its good, but i think it is. before i pulled it out i checked it and had just a little over 12V. i put connect battery to booster/charger at crank setting and still nothing. i'm wondering if starter no good. so i pulled starter, will check it and battery tomorrow - anybody know what kind of amperage a starter like this will draw with no load? if battery and starter seem okay, any ideas on what to check next? i checked cables and connections and all look good? maybe solenoid? thanks to anybody with any ideas.....
 

Chris1956

Supreme Mariner
Joined
Mar 25, 2004
Messages
27,959
Re: 1979 140 Merc not charging?

Does that motor have a distributor ign or multiple coil ign? On distributor engine ign power is supplied by the battery, not the stator. Check the rectifier for proper operation. It is a normal bridge of 4 diodes.
Stator will provide AC voltage to the rectifier. A multimeter can test for it.
Inspect the battery cables. Run your fingers along their length feeling for spongyness or bumps. Corrosion can corrode them under the insulation.

That starter could pull 150A I would think when starting the motor.
 
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