A new issue with my 1984 johnson 75.

Fed

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So its time to replace the stator?
Not from what you have said about the test results so far. (No mention of yellow to yellow reading)

Hooking the tach directly to the battery & grey wire and having it work correctly should tell you the tach is not receiving 12V + grey signal via the controller.

A loose battery connection can take out a rectifier so test it.
 

JoshKeller84

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Just went out and checked again. Yellow to yellow produces no resistance. Yellow/grey no resistance. Yellow wire produces no resistance unless i rotate the flywheel slowly by hand. Checked and verified all connections and terminals were clean and tight. The new rectifier is now tested bad. Weird thing is, i hooked my tach signal wire to the yellow/grey wire and got nothing. Hooked it up to the yellow wire and it worked, but still had the drops and erraticness
 
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Fed

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When you test yellow to yellow does the meter read ZERO or INFINITY?

Normal resistance would be about 1.0 Ohm (Very close to ZERO or NO resistance)
 

JoshKeller84

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The meter says OL, except on yellow when slowly turning flywheel - it will spike in the 100's
 
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JoshKeller84

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At this point, im ready to get a spark plug wire tach, and run it as is. Is this a problem? What else is suggested to get this thing running properly. I just cant figure out how if something isnt wrong with the stator, why the tach gets erratic when hooked directly to the yellow wire.
 

Fed

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I just cant figure out how if something isnt wrong with the stator, why the tach gets erratic when hooked directly to the yellow wire.
Because you don't have a solid 12 Volts to the tach.
 

Fed

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From your first post.
Hooked the tach directly to the battery, and the signal wire directly to the grey terminal on the engine, and it worked perfectly.

It's to believe you have since developed a faulty stator.

So that only leaves a wiring problem.

Continuity of the grey wire between the motor terminal block & the back of the tach including the controller & it's plug/socket.
Or​
Not supplying the tach with a solid 12 Volts.
Don't rely on the tach light or your fishfinder to indicate you have 12 Volts at the tach.
 

JoshKeller84

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From your first post.


It's to believe you have since developed a faulty stator.

So that only leaves a wiring problem.

Continuity of the grey wire between the motor terminal block & the back of the tach including the controller & it's plug/socket.
Or​

Not supplying the tach with a solid 12 Volts.
Don't rely on the tach light or your fishfinder to indicate you have 12 Volts at the tach.

Yes, when i replaced the recitifier, it worked perfectly for about 20 minutes. Then it got intermittant. The tach stopped, the battery stopped charging. After that, the rectifier was tested as blown.

I was having issues with the tach connection at first, which was resolved by discovering the previous owner hadnthe tach plug wired together wrong.

The motor had a bad rectifier on it when i got it, and the next one lasted 20 minutes.
 

Fed

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Here's what I'd do Josh, the tests should only take 10 minutes but have to be done by the book.

Test the stator.
Test the rectifiers, find a good one or buy a new one & fit it.
Solder the cut lead inside the controller then test for continuity from within the controller to the back of the tach.
Clean & tighten all connections on the battery.

See where you stand after that.
 

JoshKeller84

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I am 100% sure the connections at the tach are correct and fixed now. I verified them 20 times with the meter, as I have with the two rectifiers. I tested the new one I bought before installation by the omc service manual (test ground lead to case of rectifer, then test each wire to get a reading. Then reverse test to get no reading in another direction - now after its blown, I get readings in both directions), to be sue it was working, in case i needed to exchange it. This leads me to believe I either have a faulty stator, or a reason the rectifier has blown after just 20 minutes. I ordered 2 more new rectifiers, and will sacrifice one if I need to, and test it after tightening all connections. Is it true that the tach will read the pulses off the stator, which means It should run properly off the yellow wire from the stator? The tach still reads erratically hooked to the yellow stator teminal (not bouncing like its losing power, but dropping, rising fast, etc like its losing its signal). This is on the switched ignition plug AND directly hooked to the battey.
 

JoshKeller84

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yes, i noticed the terminal. There is no signal on the grey wire for the tach, nor if i hook the tach up to the yellow/grey wire. It works, but the tach bounces around when hooked up the yellow only wire. which leads me to believe there is no power reaching the yellow/grey wire. Does the current form a loop going from the yellow wire, thru the rectifier, into the yellow/grey wire back into the stator? Or does it flow through both yellow and yellow/grey wires into the ground of the rectifier?


I took a file and ground down the rectifier post to bare metal before putting on the new rectifier.
 
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Bosunsmate

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Well i tested the stator and one of the leads is coming back as having resistance. Hooked the tach up directly to the yellow wire and it would still bounce around occasionally. Im assuming this confirms i need a new stator?
Well you said this.
This is your problem
 

Bosunsmate

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Well ive done all the test youve suggested and its still popping rectifiers. Just trying to provide all the information on the tests and things ive tried thus far
Youve had many responses and you havent shown any appreciation for it, it gets tiring
 
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