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Bad Stator or Rectifier?

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Travis2033

New member
I have a 1991 Johnson 40hp on a 21' Party Barge.Model# TJ40ELEIA. My problems are that the tach doesn't work, if it does it works very intermittently right when I start the motor, the needle sometimes jumps around a bit then usually zero's out within a couple minutes on the water, if it works at all.I have replaced the Tach, the old Tach behaved the same way. I'm pretty confident everything on the tach end of things including wiring is ok. I'm thinking that it must be a bad signal from the Stator.
The other issue I have is I don't know if the battery charging system is working. I checked the battery before starting with a multi meter, It reads 12.4 I started the motor up on muffs and checked it at idle it reads 12.3. Isn't it suppose to go up when the boat is running, not down? Should I try changing the rectifier first and see if that solves my problems? I'm thinking the problem is more likley the Stator.I believe the Stator sends the signal to the tach. I think both the stator and rectifier have to do with the charging system. Should I just replace both? I have never pulled a flywheel off before. so I will need to pick up a flywheel puller and flywheel wrench. anything else I would need? Thanks in advance if you know more about this than I do!
 
Do the following test

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(Testing Tachometer With Water Cooled Regulator/Rectifier)
(J. Reeves)

A quick check is to simply plug in a another new tachometer as a piece of test equipment. If the new tach works properly and the old tach didn't, obviously the old tach is faulty.... but usually boaters don't carry around a spare tach (see below).

A faulty rectifier wouldn't damage the tachometer, the tachometer simply wouldn't work. This is due to the fact that the tachometer operates off of the charging system and the rectifier converts AC voltage to DC voltage, enabling the charging system. A faulty rectifier disables the charging system, and the tachometer simply doesn't register.

However.... those water cooled regulator/rectifiers that are used on the 35 ampere charging systems (and some others) bring into play a different type problem, and as you've probably found out, they are really a pain to troubleshoot via the proper procedure. There's an easier way.

The tachometer sending/receiving setup operates off of the gray wire at the tachometer. That same gray wire exists at the engine wiring harness which is connected to the engine electrical terminal strip. You'll see that there is a gray wire leading from the regulator/rectifier to that terminal strip, and that there is another gray wire attached to it. That other gray wire is the wire leading to the tachometer which is the one you're looking for.

NOTE: For the later models that DO NOT incorporate a wiring terminal strip, splicing into the "Yellow Wire" mentioned will be necessary.

Normally the Gray wire leading from the tachometer is attached at the terminal strip to another Gray wire which leads from the water cooled voltage regulator/rectifier...... remove the gray wire that leads to the tachometer. Now, find the two (2) yellow wires leading from the stator to that terminal strip. Hopefully one of them is either yellow/gray or is connected to a yellow/gray wire at the terminal strip. If so, connect the gray wire you removed previously to that yellow/gray terminal. Start the engine and check the tachometers operation, and if the tachometer operates as it should, then the regulator/rectifier is faulty and will require replacing. If the tachometer is still faulty, replace the tachometer.

If neither of the yellow wires from the stator is yellow/gray, and neither is attached to a yellow/gray wire, then attach that gray tachometer wire to either yellow stator wire, then the other yellow wire, checking the tachometer operation on both connections.

I've found this method to be a quick and efficient way of finding out which component is faulty.... the tachometer or the regulator/rectifier. It sounds drawn out but really only takes a very short time to run through. If the water cooled regulator/rectifier proves to be faulty, don't put off replacing it as they have been known to catch on fire with disastrous consequences.
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so coming from the rectifier I have a red wire, a yellow, a yellow with blue stripe, and a yellow with grey stripe. I also found the grey wire that leads to the tach. The yellow grey wire is connected to the same terminal as the grey wire along with another yellow grey wire that leads under the flywheel, (I'm assuming to the stator). There are 3 wires coming from the stator a yellow, yellow blue and yellow grey. so right now the yellow grey from the stator, the yellow grey from the rectifier and the grey to the tach are all connected to the same terminal. Are you saying to disconnect the yellow grey coming from the rectifier and then fire it up and see if the tach works?

edit- Just to further clarify we would be taking the rectifier out of the equation and would just have the yellow grey from the stator connected to the terminal along with the grey wire to the tach. Then if the tach works correctly then I know I have a bad rectifier, if not then the stator is the problem?
 
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Travis2033 said:
so coming from the rectifier I have a red wire, a yellow, a yellow with blue stripe, and a yellow with grey stripe. I also found the grey wire that leads to the tach. The yellow grey wire is connected to the same terminal as the grey wire along with another yellow grey wire that leads under the flywheel, (I'm assuming to the stator). There are 3 wires coming from the stator a yellow, yellow blue and yellow grey. so right now the yellow grey from the stator, the yellow grey from the rectifier and the grey to the tach are all connected to the same terminal. Are you saying to disconnect the yellow grey coming from the rectifier and then fire it up and see if the tach works?

edit- Just to further clarify we would be taking the rectifier out of the equation and would just have the yellow grey from the stator connected to the terminal along with the grey wire to the tach. Then if the tach works correctly then I know I have a bad rectifier, if not then the stator is the problem?
Click to expand...

Yes, not in those words, but that's what I'm saying.... What is the Yellow/Blue stator wire attached to?

DO NOT assume the stator is bad unless there is a sticky looking substance leaking/dripping from it down on the powerhead OR its ohm readings are wrong.
 
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The Yellow/Blue wire from the stator is attached to another Yellow/Blue wire that goes to the Rectifier. I will try that test and let you know what happens. I'll look in my repair manual to see if I can find the ohm test for the Stator. Thanks for the info!

I did have a sticky substance last year that was on some of the wiring connections, and tilt trim relay connections that was causing the tilt trim to malfunction, but I got that all cleaned up and tilt trim switches work again.

edit- Now that I had a chance to look at the motor, there is a sticky brownish looking substance that is coming from under the flywheel. It's not dripping or currently leaking but it left a trail. This motor hasn't really run since October last year until I ran it for a couple minutes yesterday on muffs.
 
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I did the test and the Tach seems to be working flawlessly! I'm going to order a new Rectifier. Thanks so much! rectifier will be much easier to replace than the stator!
 
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