Evinrude E-NATION, for those dedicated to water, power, fishing and fun
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Captain
Posts: 55
Registered: ‎09-13-2011

Tach Question

Here's one for you Bill:

 

I just installed a new (BRP) tach on the boat, Put it in the water, and the tach works great up to 3000 rpm.

 

Then when I wick it up to WOT, the tach only goes up to about 3800.  But the motor is clearly spooling up to its 5000 to 6000 RPM range (Like you, I've been around these things a few years and can tell)

 

The 98 O-Pro 200 is turning a 15x 17 SST on a 22ft center console (2690 lbs.), so I know its not over propped that bad, if at all.

 

When I installed the tach, I followed the instructions and adjusted the pole swith behind the tach according to the instructions for my motor (thats why it seems to read fine at slower speeds)

 

I'm wondering if I the contacts are dirty inside the tach.

 

Have you ever heard of this?  I want to dial in the right prop, but i can't get the tach to spool up with the engine at WOT

 

 

 

 

Captain
Posts: 34
Registered: ‎06-12-2017

Re: Tach Question

can you count the magnets under the flywheel?

what P setting did you choose?

 

I suspect that the voltage regulator is faulty...

but we need to rule out the tach as being an issue.

 

I hate to point you to a different forum, so I'll copy/paste an article by a guy named  Joe 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.

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 watercooled regulator/rectifiers that are used on the 35amp 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.

Remove that 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 efficent 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 disasterous consequences."

 

 

Captain
Posts: 55
Registered: ‎09-13-2011

Re: Tach Question

[ Edited ]

You know, as i read your reply, it dawned on me that my Voltmeter was always over to the charge side when the engine was running, but not in the usual way.

 

In normal conditions, after the battery is charged, the regulator lessens the juice and the volt meter needle comes back to more "neutral" position in the center of the guage face. Mine stays almost hard over all the time.

 

The battery is not discharging, but its sounds like the Regulator is not shutting down the charging circuit after the battery comes up to full charge. 

 

This leads me to believe my Voltage Regulator/Rectifier assembly is out to lunch, hence the tach operating only up to a certain RPM level.

 

I just ordered a new Regulator/Rectifier for the motor because I bet this will solve both of these problems.

 

Thank you for the insight!

 

Bill - Feel free to chime in, would love to hear your thoughts, espcially if you think I'm of base here, but i don't think I am.

Captain
Posts: 34
Registered: ‎06-12-2017

Re: Tach Question

I'd replace your volt thingy to a voltmeter than actually shows the voltage....

 

but yeah the regulator spits out both the recharge volts and tach pulse....not too cheap, but an easy replacement.

Captain
Posts: 55
Registered: ‎09-13-2011

Re: Tach Question

[ Edited ]

I checked the OMC Tech manual last night, the volt meter is supposed to settle back to about 14.5 v during normal operation. Mine is not doing that, it seems to be constantly charging for as long as I run thew motor. 

 

TheTech manual says to check the Stator to make sure its not grounded out, before replacing the Regulator/Rectifier, but my tach works, (until about 3/4 throttle) and the motor is is not discharging the battery, so i know thats its ok

 

The Voltmeter is new.

 

Other than that, the motor runs great.

 

 

Admiral
Posts: 8,402
Registered: ‎07-14-2011

Re: Tach Question

 

 

If you have not done this already, remove the flywheel and check for loose or cracked magnets and for a loose inner magnet hear the center.

 

Inspect the stator and look for any melted plastic insulation dripping from it onto the top of the engine block. A bad regulator can cause the electrical overheating of the stator frame and the charge coils.

 

If you have a DVA meter and a service manual, you can connect them to the gray tach pulse wire and watch the output as the engine runs up to WOT. A quicker way is to substitute a known good tack, just plug it in to see if the symptoms are still there.

 

Check your battery with both a load tester and one of the newer electronic testers, just to be sure it is of adequate capacity and can deliver its full output if needed.

 

 

 


"There is never just one thing wrong with a boat";
                    -- Travis McGee, main character in a book series by John D. McDonald 


 



***************

The factory recommends that a properly trained technician service your Johnson or Evinrude outboard motor. Should you elect to perform repairs yourself, use caution, common sense, and observe safety procedures in the vicinity of flammable liquids, around moving parts, near high-temperature components, and working with electrical or ignition systems.

The information offered here is only general in nature and should not be construed as complete factory approved procedures, techniques, or specifications. Always use the proper service manual for your motor, up-to-date service literature, the correct tools, and have an understanding of how to proceed with troubleshooting and repair methods. If you are unsure or uncomfortable with a procedure, a situation, or a technique, enlist the services of a factory trained technician.