Tach not working. - The Hull Truth

Bluemelvin · 06-14-2003, 05:26 PM

Hey guy's, need alittle help. When we started out today the tach jumped a bit then just stopped working. Also the volts dropped to 11.9-11.7. I checked all the battery cables and they were in good shape but I haven't been able to get to the motor yet. Will put it on the work rack tommorrow and start checking stuff there. Could it be the voltage regulator? Its a 1999 200 Johnson.
Thanks for any suggestions on were to start.

Larry Carnahan · 06-14-2003, 05:30 PM

Many times a tach problem can be traced to the rectifier, especially if the engine has ever overheated.

LarryC

CaptDG · 06-14-2003, 05:52 PM

Yup, sounds like the rectifier/regulator or one of it's connections. Give all of those, plus the usual other harness connections a good once over.
A good shop manual will give you the procedure for checking regulator and stator outputs. Given the cost of some the new rectifier/regulators it is worth a little time just to be sure. Most parts places won't take back electrical parts once they have been out ofthe box.

Bluemelvin · 06-15-2003, 02:39 AM

Thanks guy's. I am not sure if it has overheated or not. I have only owned it for about 8 months. Hopefully I can find a loose connection today instead of having to buy new parts.

lakensea · 06-15-2003, 05:05 AM

Could also be the charge stator as it supplies AC power to the regulator/rectifier and the tach gets its pulse from one of the stator wires.

Bluemelvin · 06-15-2003, 07:23 AM

Thanks lakensea. I was thinking about that also but kind of unsure how to check it. I'm really hoping thats not the problem as that sounds expensive.

whanks · 06-15-2003, 08:02 AM

If the diode fails, the tac will stop working and the battery will not be charged. The diode I've seen on Johnson outboard motors is about 1.5 inches in diameter and on the port side of the engine. It can be checked with an ohm meter. Good luck.

Bluemelvin · 06-21-2003, 05:46 AM

How often does a stator go bad? Could a bad rectifier damage the stator or the stator damage the rectifier? I have been told to change both of them which kinda makes sense. Oh well, its just money huh.

Mud Runner · 06-22-2003, 08:13 AM

I don't know who told you to change both but if it's your mechanic, I would get a new one. A bad battery in a two battery system can cause a surge big enough to cause the rectifier diode to fail. I've changed many rectifiers and never had to change the stator. That's not to say they don't go bad. When cars had separate regulators, you didn't change the alternator when it went bad. This is the same situation. In fact, years ago when money was tight and the OMC shop wanted $65 for a rectifier, I went too Radio Shack and bought a full wave bridge rectifier for about $2.50 and installed it. All the rectifier does is take the AC power that the stator produces and converts it to DC power. The only thing you have to keep in mind is to size the rectifier for the proper amps for your system. The only difference is that the OMC part is epoxy clad and in an aluminum case to dissapte heat and act as the ground. A rectifier/regulator is a different case all together.

Mud Runner · 06-22-2003, 07:48 PM

Bluemelvin,
Beat me with a wet battery cable. I just realized that you have a rectifier/regulator in your 200 hp. It's that same as in my 150hp. It sits on top of the engine under the black pastic cover for the optical sensor. It's between the cylinders. The thing you have to watch for is that it sits in the cooling water for the engine. You have to be careful when you repace it so that the gasket is installed properly or you'll look like a sprinkler system when you start the system. A new one is about $200. I replace mine last year and the old gaske had a raised ridge which made a good seal. The new one was flat and leaked but I was lucky I could reuse the old one.

Bluemelvin · 06-24-2003, 04:24 PM

Thanks Mud. Thats right it is in between the top 2 cylinders and the flywheel. Parts man said $211. owch.

Hydro · 06-25-2003, 05:16 AM

Same exact motor, same exact problem last year. I recall paying about $170 for the regulator and installed it myself. Turns out they changed the design on the regulator and i was left hanging with an extra wire. None of the mechanics knew what the ** was going on until they called OMC/Bomb. So now i've got an extra wire dangling off the thing. Works/runs fine though. Replaced both batts last month and those bad batts might have been the problem. My advice - take it to the pros and spend the extra $$$.

If the beer don't taste like fish, you ain't doin' it right.

Bluemelvin · 06-25-2003, 04:19 PM

Ya know Hydro, I was thinking I need to change that battery also. (only has one) When I got the boat in Sept the battery was dry as a bone and dead. Filled it with water and recharged it and it has been fine ever since. Still think it is part of the problem some where down the line. Not to mention I don't have complete confidence in it.