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Voltage Regulator fried

Rlfrazee's Avatar
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10-19-03, 07:35 PM   #1  
Voltage Regulator fried

I have a voltage regulator that is fried but a little history is needed first. Motor is a 1995 90 hp Mariner electric start serial#OG163371. About year ago the stator went out on this boat motor and was replaced with red stator part#398-832075A5 16 AMP. First day on the water after this I noticed my tach wasnt working. Got home and started checking things out using my maintenance manual I ordered from the factory. Found that boat mechanic at mercury dealer left the two yellow wires coming from my stator to a terminal block then to voltage regulator disconnected at terminal block. Noticed where the two yellow wires from stator had been arcing against engine block. Not sure if or remember if these wires were making contact with two yellows going to voltage regulator. This terminal block is also where pulse/send wire from regulator to tach is connected so follows why it didnt work (all wires at terminal block were disconnected) Dont know why he disconnected tach though since it wasnt necessary. Anyway reconnected wires per description and wiring diagram in manual. Pretty straight forward connection. Anyway shortly after this my starting battery (it was only about a month old) started becoming weak and over a period of months needed recharging several times. Then the tach failed just the other day. Anyway a week ago decided to have battery checked and it was bad. Replaced it. Being suspious I did amp check as per manual instructions after replacing battery. Battery voltage with engine running was 13.54 VDC. However huge number of amps ( 38 ) at 3000 rpm should be 18. Not at the battery but amp meter connected as manual described. Started looking at voltage regulator since it would be suspect. Noticed a brown gel running down side of engine directly below voltage regulator. Looked closer and saw small melted solder beads. Took off voltage regulator, turned regulator upside down and has big hole burned in it. The regulator is the small type part#815279-3. It is also the rectifier. So my questions are....... 1.) Could the regulator have been bad in the beginning causing the stator to go bad ? This seems unlikely since it was the motor not starting that led to bad stator a year ago (no spark) and new stator, even with voltage regulator bad, is working fine on the ignition side at least.....2.) Is there anything I need to be sure of after new voltage regulator has been replaced?....I figure charging circuitry in regulator has been out since battery problem began and finally tach circuitry fried recently. The dealer who did the work a year ago has agreed to make things right with me since he feels the problems were a result of his tech not completing the original install correctly. He says he will check everything out for me after they replace regulator. But Im a little " gun shy" as they say.......Thanks RL

Last edited by Rlfrazee; 10-19-03 at 10:40 PM.
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BoatMech's Avatar

Join Date: Dec 1999
Posts: 592

10-19-03, 10:39 PM   #2  
I will be brief, Yes the regulator can cause a stator failure.
Yes the stator could have been bad, and no it does not
necessarily need replacement after the regulator "burnout".
The Tech can properly diagnose the output of the yellow wires
and determine its condition.
It is good of you to go back to the dealer and give them
a chance to make it right. Things happen sometimes in the shop
distracting a tech. I wish it wern't so.
Thanks also for the concise report.

Rlfrazee's Avatar
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10-19-03, 10:52 PM   #3  
Thanks for reply Scott. Im probably just going to run the boat and see how things go after I get it back from shop.....RL

jughead's Avatar

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10-29-03, 04:55 PM   #4  
I would'nt be upset with 13.54v on the battery but the charging current seems excessive. A normal 12 auto battery wants to see about 13.8 volts under normal charging conditions. Perhaps the battery has a shorted cell. You are probably overloading the charging system and perhaps the regulator is bad. Checking the voltage again with a known good battery should tell you if the regulator is working OK. If your charging system is working into a battery with a shorted cell and the regulator is defective you would probably have the kind of readings you have. The defective regulator could have caused the battery to fail with a shorted cell so you see a reduced charging voltage along with excessive charging current.

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