very high alternator voltage.

[rca1pollock]

Help..have 1984 mercruiser 120 serial #66----.. battery died leaving me stuck on lake...checked voltage output alternator and was very high! Figured it was internal voltage reg or alternator so I replaced with same ac delco 3 wire. Still have 32-37 volts at Orange output wire! Battery has been replaced. Battery terminals never read more than usual 12+ volts. Even at high rpm. Slowly over few trips it discharges. What would cause HIGH output voltage..bad ground somewhere..short..

 

[NHGuy]

Check your grounds. Then verify the voltage with another device. Then if it's still way up there perhaps something in your wiring could be ruining the voltage regulators.

 

[rca1pollock]

i will take off all ground connections and clean up corrosion...my multimeter is accurate...

 

[FreeBeeTony]

Sounds like the output of the alt is not connected to the battery............

 

[rca1pollock]

that may be...orange output wire from alt. goes to starter..i think some type of 90 amp fuse that looks nothing like any fuse i,ve seen..maybe that's blown (open). gotta figure out how to test that fuse?

 

[rca1pollock]

what should resistance be for across fuse

 

[NHGuy]

umm if it's open replace it, or if it's a breaker reset it. I believe resistance should be darn near zero, or full continuity, and it should trip when it experiences a 90 amp load. Resistance isn't likely an issue when the 90 amp trips. Check for bare wires shorted to ground and look along the harness to the alternator too. At one point there was some kind of Mercruiser recall for similar fuse pops.

 

[Bt Doctur]

If you have 12v at the alt stud with the engine off ,your connected to the battery. If you don't, it could be the 90A fuse is shot. You can bypass it .

 

[Bt Doctur]

~~If you have 12v at the alt stud with the engine off ,your connected to the battery. If you don't, it could be the 90A fuse is shot. You can bypass it .

 

[rca1pollock]

took fuse off.. measured it at about 6.5 m on meter! i think thats thousand or hund thous. ohms. must be bad 90 amp fuse.will replace tomorrow. was to scared to run pos lead right through solenoid without fuse..didn't want any fried harness'

 

[rca1pollock]

wow!! thanx guys! new fuse FIXED everything...i've been chasing this thing awhile..output from alternator now 14v ...battery now charging! only 1 more question...i have 3 leads (huge red, large red and orange from alt) that hook up to solenoid and fuse attached to it..obviously huge red goes in front of fuse(to batt), orange goes on outside of 90 amp fuse, does large red wire that goes into harness.. go onto fused orange alt side or on side of solenoid (staight from battery)?:happy::happy::happy::happy:

 

[Bt Doctur]

straight to the large lug ,not fused. that red is your main system power that goes to the 50A circuit breaker

 

[rca1pollock]

great! thanx for all...boy have i been learned alot..gonna take her out tonite for some walleye..happy boating all!