# Johnson outboard 50hp tachometer please help



## riverrat36 (Apr 8, 2017)

1999 johnson 50hp model J50PLEEA 

My tachometer has always worked, also my fish finer normally shows increase voltage for my batteries when my outboard is running. I looked at the tachometer yesterday and it wasn't working also my fish finder wasn't showing increase voltage to my batteries(usually when the outboard is on it jumps to 14volts or so) . Now When I turn the key for power the needle bounces a bit and then when the motor starts the needle barley moves to 200rpms. I checked the voltage to my battery while the motor was idleing and my battery voltage doesn't change with the motor running. So the motor is not charging the batteries. Also I used a multimeter to check it, and tested on the diode setting on the voltage regulator
Red to yellow .503v
Red to 2nd yellow .506v
Red to grey. 1.907v
The purple wire when attached to everything else shows zero. Either way even with the leads swapped around on the multimeter

I have done some research and the tach not working points to my voltage rectifier being the problem. Is there anything else it could be beside the rectifier? I keep chasing problem after problem and am tired of throwing parts at this motor. This year I've rebuilt the carbs, new fuel pump, new plugs/wire/boots, and new water pump rebuild kit.
Thanks in advanced for any help!!!!!!!


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## bustedrod (May 13, 2015)

on my merc the rectifier is a small square with power wires in and out. it can be checked and the part should be available


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## riverrat36 (Apr 8, 2017)

Yeah I tried checking it and comparing it to videos on YouTube. The wires on mine are two yellow wires, one grey wire, red, and purple. I found the part it is part johnson part number 585001. But it's $160. I was just hoping to make for sure that this is the problem because I can't afford to spend any money on parts that aren't the problem.


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## My Demeyes (Aug 2, 2010)

riverrat36 said:


> Yeah I tried checking it and comparing it to videos on YouTube. The wires on mine are two yellow wires, one grey wire, red, and purple. I found the part it is part johnson part number 585001. But it's $160. I was just hoping to make for sure that this is the problem because I can't afford to spend any money on parts that aren't the problem.


I have a 1992 Johnson 90 hp, tach quit working, replaces voltage regulator/rectifier tach works fine now.


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## capt j-rod (Feb 14, 2008)

Yep... bad news is it's all under the flywheel


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## UFM82 (Apr 6, 2004)

That's not too bad to pull the flywheel though. One nut and a steering wheel puller will pop it off. You can "borrow" that at a car parts place. Just don't loose the key that sits in the crank.


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## riverrat36 (Apr 8, 2017)

The rectifier on mine is on the side of the motor. I'd buy a new one but mine is a regulator/rectifier combo so it's $160. So I don't want to make a $160 guess, just in case it's not the regulator/rectifier, and maybe it's the stator? Cause I looked online and It looks like the stator has 2 functions. The first is to create power that goes to the regulator/rectifier to charge the batteries and the second to crate spark. And it says one of those functions can fail while the other still works.


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## steelneyes2 (Jul 19, 2011)

Three words..... Factory Service Manual..... You need to test the static resistance of the stator and the regulator/rectifier. most likely the regulator/rectifier has shorted to ground which will not give you any tach signal. If the stator went out, the motor usually wont run very nicely because the stator also provides power to the motor once it starts to keep the electrical system (separate from the ignition) running. Go to CDI Electronics web page, they made most of the electronics for that motor. They have a complete ignition trouble shooting guide you can download for free. There is no guesswork in diagnosing an ignition system if you follow the steps they outline. You obviously have a voltmeter and if you get a $30 DVA adapter, you can diagnose any issue that motor has with the troubleshooting guide they provide. PM me if you need any more help.


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## FAB (May 26, 2013)

riverrat36 said:


> Yeah I tried checking it and comparing it to videos on YouTube. The wires on mine are two yellow wires, one grey wire, red, and purple. I found the part it is part johnson part number 585001. But it's $160. I was just hoping to make for sure that this is the problem because I can't afford to spend any money on parts that aren't the problem.


Look at ebay, there are several on there right now for around $70 with free shipping. Same part number for same engine model.


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## riverrat36 (Apr 8, 2017)

Thanks FAB I actually just ordered one off of there last night for $83 shipped, the guy said it was put on the motor and only used a couple hours. Crossing my fingers that this solves my issue. Although I found a CDI troubleshooting guide and I tested the resistances on my stator, all the wire resistances were in spec except for the orange to orange/black stripe wire. That was supposed to be 45-55ohms and it was 411ohms


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