Re: Rectifier volts drop from 14-4volts after 10 minutes of idle, then it starts miss
The "coil and lamination" is the coil that powers the ignition system
The stator assembly are the coils that generate the power for battery charging via the rectifier.
(Some motors have the two combined into one unit)
BTW
J40TLCEC is the model number for a 1989 model not 1991
You can check the AC volts going to the rectifier with an ordinary AC voltmeter
It is a four wire rectifier ? ?
Between the yellow and the yellow/gray wires you should get something that rises well above 12volts, to 18 or something like that as you rev the engine. Likewise between the Yellow/blue and the yellow/gray. I dont know what you'll get between yellow and yellow/blue.
You can test the continuity of the stator coils, if you disconnect it, with an ohns meter. you should get a low reading between any of the wires but the reading between Yellow and yellow/blue will be double the other readings.
You can test the round three and four wire rectifiers by following Joe Reeves' instructions
Perhaps your engine does not have the water cooled regulator/rectifer but rather incorporates the smaller 3 wire rectifier which sits just forward of a vertical electrical strip on the starboard side of the engine.
If so, a failed rectifier would knock out the tachometer. See the following.
Remove the rectifier wires from the terminal block. Using a ohm meter, connect the black lead of the ohm meter to the rectifier base (ground), then one by one, connect the red lead of the ohm meter to the yellow, yellow/gray, then the red wire (some rectifiers may also have a fourth yellow/blue wire. If so connect to that also). Now, reverse the ohm meter leads and check those same wires again. You should get a reading in one direction, and none at all in the other direction.
Now, connect the black lead of the ohm meter to the red wire. One by one, connect the red lead of the ohm meter to the yellow, yellow/gray, and if present, the yellow/blue wire. Then reverse the leads, checking the wires again. Once more, you should get a reading in one direction and none in the other.
Note that the reading obtained from the red rectifier wire will be lower then what is obtained from the other wires.
Any deviation from the "Reading", "No Reading" as above indicates a faulty rectifier. Note that a rectifier will not tolerate reverse polarity. Simply touching the battery with the cables in the reverse order or hooking up a battery charger backwards will blow the diodes in the rectifier assy immediately.
But if you use a digital meter use it on the "Diode test" setting not an ohms range. If you have no diode test setting the use the highest ohms range.