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

 

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.

 

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

 

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.

 

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.

 

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.

 

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