Charging & Tach issues

[Banger]

I have a 1996 Johnson 115, seems not to charging battery, reads 12.6 volts running or not. Tach will work sporadically and only for a short period, maybe 10 seconds or not at all. From other posts seems like I am looking at a voltage regulator, mine has 5 wires coming from it. I am also using a deep cycle battery due to my regular battery failed. Volt test was with regular battery? Thanks

 

[joereeves]

Sounds like the voltage regulator/rectifier assembly has failed... BUT... do the following test to make sure. This will tell you if this is the case OR if the tachometer is failing and interfering with the circuit.

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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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[l-driver]

Voltage regulator sounds like the problem.
my tach and charging quit on me after I did a engine rebuild. Replaced regulator -no change.
Took off flywheel and found a wire slipped under the edge of the stator when assembling.
removed yellow wire and repaired crushed insulator - all works fine now.

 

[Banger]

Hey thanks Joe Reeves, took off gray wire and tach started working. Going to change regulator, one question, when removing fly wheel what is the best thing to use to hold fly wheel from turning. I was looking at strap wrench but doesn't seem to big enough.

 

[fdrgator]

Get a bigger strap wrench. Or if you want to go all out, go to an auto parts store and get a flywheel turning tool Car mechanics use them all the time to remove/reinstall clutches and transmissions.

Or go the cheap route and make your own strap wrench from a piece of 2 x 2 lumber and a piece of nylon strap.