1984 Mercury 115 Rectifier ??

TripleB

Cadet
Joined
Sep 6, 2012
Messages
21
I believed I had a problem with the rectifier on my 1984 115 hp mercury ..... My trouble/problem was when I went to take off in the boat I had no hole shot at all, couldn't get it up on plane. So I did a little reading and tried my hand at some trouble shooting. I started by removing the 2 yellow wires that run from the stator to the rectifier, fired it up and it ran like a bat out of hell!! So ... all proud at myself for figuring out what was wrong with the motor I removed the old one and headed home. When I got home I did a search for testing a mercury outboard rectifier and found this.


1. Place/set your multimeter to the 1000 ohmmeter reading (RX1K, R X 1000, etc). See picture below.
2. Place the RED lead to the ground (G) and place the BLACK lead to A and C alternating. You should show continuity.
3. Place the BLACK lead to the ground (G) and place the RED lead to A and C alternating. You should NOT show continuity.
4. Place the BLACK lead to the terminal (B)) and place the RED lead to A and C alternating. You should show continuity.
5. Place the RED lead to the terminal (B)) and place the BLACK lead to A and C alternating. You should NOT show continuity.
6. If your results differ, then the rectifier should be replaced.


I did the test as show above and my readings where completely opposite of the above test, so figuring I had it all figured out I order and new rectifier.

Well today my new rectifier comes (Sierra 18-5707) and I grab my meter and do the same test and .......... shows results opposite of above prescribed test.

So now I have to ask .... 1. Is above show test incorrect? if its not, did I get a bad (new) rectifier? ... and ... 2. If my rectifier isn't bad and a bought a new one for nothing what else could be wrong with my motor that it runs crappy with the stator wires hooked up to the rectifier, and runs like a champ as soon as there disconnected?
 

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Maxz695

Guest
Re: 1984 Mercury 115 Rectifier ??

is the tach wire hooked up to one of the yellow wires Might be a gry wire. The tach could be affecting the charging system if bad or grounded
 

Chris1956

Supreme Mariner
Joined
Mar 25, 2004
Messages
27,036
Re: 1984 Mercury 115 Rectifier ??

Your test is a bit hard to follow. You need to test the 4 diodes in the rectifier. Diodes are one way gates. So, if you test red lead on G and black lead on A, and you get continuity, switch the leads and retest, and you should see no continuity. If the red lead on G and black lead on A shows no continuity, switch leads and you should see continuity.

Do the same test for G and C, B and C and B and A. You should always see contunity with the leads one way and no contunity with the leads the other way. You must use an analog meter or a digital one with a diode test setting.

If the a diode is open or shorted both ways, the rectifier is bad, which is likely what you have.
 
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