Tachometer on a 150 Johnson fast strike 1992

beatle

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Aug 31, 2018
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Just replaced the wiring harness on my 1992 Johnson fast strike and engine is running nicely now.. Unfortunately the tachometer is not working.. It says gray wire is to tach.. Can someone tell me exactly where the tachometer is?? I have checked all connections and they are good.. I checked the gauge with a power light and it has power to it.. Any ideas??
 

Joe Reeves

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Feb 24, 2002
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I'm pretty sure that you know where the tachometer is... BUT if what you're asking really is where does the gray wire go. well.................

The gray wire should be included in the wiring harness... is it?

At the tachometer, the gray wire is to be attached to the "S" (sensor) terminal of the tachometer.

At the engine, it should be attached to the gray wire terminal leading from the voltage regulator/rectifier.

If this isn't the answer you're looking for... what was the question? You need to be specific in what you're speaking of.
 

beatle

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Alright Joe you got me.. It was a vague question.. I was looking for where the tachometer senses at the engine.. You answered that question. I changed the connection at the voltage regulator/rectifier and no luck.. I put a ohm meter on the connection that goes into the regulator and to ground it reads 12 ohm.. The grey wire going back into the harness going toward the boat I get nothing on, I am not a electrician so I really don't even know what that means.. Anyway.. I don't think a new wiring harness from cdi would be bad … How could I test to see if the regulator rectifier is bad?
 

jakedaawg

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Did the tach work before you put the harness in? Which harness did you install, boat side, engine side, both?

last few times I got something from cdi the wires were in the wrong terminals. (Was a power pack twice)
 

beatle

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So I installed a new harness on the engine side. The tach worked fine until then.. I double checked every connection, all were good.. Starting to think maybe my regulator rectifier has a problem.. Is there a easy test for those?
 

beatle

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So I only have four wires 2 yellow , one gray to tach and a red.
 

Faztbullet

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New style rectifier that uses sense.....make sure its has 12V on red.
 

beatle

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Yes sir it has 12 volts on the red.. Just checked it.... So tach worked before … Maybe just bad wiring harness.. Not sure where to go from here.
 

beatle

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So, I got the bright idea to bypass the wiring harness and go straight to my tachometer. I just plugged some wire in to the grey connector at the regulator/rectifier, and ran it straight to the connection on the tachometer.. voila tachometer functions just fine, Hence a crapy wiring harness. I will order another but, I doubt it will be CDI.. I will have to pay more money for OEM..

Just in case it happens to someone else.. I ordered a wiring harness off the CDI website after putting in all the data on my boat.. When it came it had 10 pins in the main connection not 8 as the original.. number was 413-5240 cdi harness.. I called CDI and they told me that they don't know why the website recommends that harness. I had them go to their own website and sure enough it told them the same thing. It was close but not the right one... I have now ordered a 413-4647 according to their tech help.. It is the correct one... Anyway, just a word to the wise be very careful when using their part finder.. The tech said he would have it corrected on the website so some other sucker wouldn't lose 200.00 bucks..
I'm not here to brow beat CDI just don't want someone else to do what I did... Lewis
 

jakedaawg

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They make it right in the end...at least for me they do. Good company to work with...at least as good as can be expected these days. Remember, everyone has a hard time finding employees that care, they do better than most.
 

Joe Reeves

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Alright Joe you got me.. It was a vague question.. I was looking for where the tachometer senses at the engine.. You answered that question. I changed the connection at the voltage regulator/rectifier and no luck.. I put a ohm meter on the connection that goes into the regulator and to ground it reads 12 ohm.. The grey wire going back into the harness going toward the boat I get nothing on, I am not a electrician so I really don't even know what that means.. Anyway.. I don't think a new wiring harness from cdi would be bad … How could I test to see if the regulator rectifier is bad?

I'm not sure what you're telling me................ If you're saying that you get 12 ohms from the regulator that the gray wire is attached to... BUT... No reading at some point further in the gray wire heading for the tachometer... that indicates a break in the gray wire or a poor connection at the regulator.

To test the regulator/rectifier and the tachometer at the same time, see the following...................

********************
(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.

********************
 

beatle

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Aug 31, 2018
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Thanks for the advice on checking the regulator/rectifier.. I will do that anyway...

CDI is going to warranty this harness out for me which is great.. would have been a 200.00 bad learning lesson... Thanks CDI.
 
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