Tachometer recycling/re-setting

[hydra23]

Hello, engine model Johnson J175exed. here are the symptoms. At 3,500rpm or above my tachmeter seems to re-set itself the alarm will sound one time and the 4 LED lights will recycle just like when the ignition switch is set to the on position. I have replace the tachmeter with an original OMC part, I have check and clean all connections including the grounds and the regulator/rectifier connections. Engine starts and runs OK. Voltage is 13.5 to 14.0 at all times. It will eventually drop to 12.5 or so to avoid overcharging. Can a bad ignition switch create this type of symptoms? Are there any other components that can create them? Do regulator/rectifiers go bad slowly or they just stop working at once? Thanks

 

[hydra23]

Re: Tachometer recycling/re-setting

Today I removed the reg/rec againg. All connections were tight and clean. The unit does not show any type of external physical damage.(heat damage,cracks on the insulation, rust, damage wires ect) I will re-inspect and clean all ground connections. Both batteries are new. And when the symptoms manifest I don`t have a drop on engine rpm`s and the tachometer never stops working, just the one beep on the alarm and the recycling tachmeter lights. If I reduce the throttle below 3,500rmps the symptoms don`t show. A bad ground connection somewhere? a faulty ignition switch? Thanks.

 

[hydra23]

Re: Tachometer recycling/re-setting

After conducting a reg/rec test (Joe Reeves) the part test out OK. I then turn to the ground connections, all were very clean and tight. Removed the ignition switch and test it. Continuity was found on the two M posts of the switch; (with the switch on the OFF position) I will replaced the switch and report the results. Why the symptoms only showed at < 3,500rmp`s I`m thinking vibration vs switch integrity. (maybe a loose body switch in the assembly)??

 

[boobie]

Re: Tachometer recycling/re-setting

The only thing I can think of is an intermited power loss from the ignition sw to the tach on the purple wire. I guess the ign sw is a good place to start.

 

[hydra23]

Re: Tachometer recycling/re-setting

Agreed. I will replaced the switch and report.

 

[Chris1956]

Re: Tachometer recycling/re-setting

Hudra, I have been chasing the same problem as you. However, my System Check Tach resets whenever I hit a bump (wave, wake..). Let me know what you come up with, as I have not found any apparent wiring problem.

 

[Silvertip]

Re: Tachometer recycling/re-setting

You don't need to replace the switch because the two "M" terminals show continuity in the OFF position. That is a correct test and that's what shorts the ignition to ground to kill the engine when you turn the key off. You apparently have an intermittent connect (ground or +12 volts) to that instrument. Have you observed a flicker on any other gauges when this happens. If so, then the power and ground are issues.

 

[hydra23]

Re: Tachometer recycling/re-setting

Silvertip, you are right. I have not observed any changes with the instruments, GPS remains on as well as the depth finder no recycling there. The tachometer is also working, only the 4 LED lights recycle at 3,500 or above rpms. Voltage at baterry is a steady 14.25. Clean and inspect all connections at reg/rec. All grounds are clean and secure. Both baterries are new. Engine runs excellent no loss of rmp or hesitation when the lights recycle. Any ideas?? My big concern is the reg/rec. As Chris states my symptoms also started after hard hitting a wave.

 

[hydra23]

Re: Tachometer recycling/re-setting

Replaced the ignition switch and took her for a spin. After running for about 5 minutes at 3,500-4,500 rpm`s the 4 tachometer lights illuminate for less than 1 second and the alarm "beep" once. From that point on the symptom repeat itself every 3-5 minutes.

At idle with the battery switch set for 1 battery the voltage will read 13.85 +-. At 4,500 rpm`s the voltage to the battery will read 12.70+-.

I have checked and re-checked all my electrical connections. Everything is clean and tight.

Can a bad regulator/rectifier be responsible for the intermittent lights? Do they just stop working at once or gradually?

All other electrical works as intended. Any feedback is welcome.

 

[Chris1956]

Re: Tachometer recycling/re-setting

Hydra, does it happen on calm water?

Your battery voltage seems acceptable

 

[hydra23]

Re: Tachometer recycling/re-setting

Chris;

It does, I replace the swicth and now the symptom is less frecuent than before, every now a then the lights will recycle and the alarm would give a weak beep. I have two new batteries when running just one of them (switch on 1)voltage at idle is 14+ crusing at 4,500 it will be 12+. (35amp system with trim) I have a GPS and a depth finder and none will turn off of recycle not even a flick....any ideas? can a reg/rec create those types of symptoms? My concern now is the system not responding to a real alarm hot, no oil, ect.
Thanks
H

 

[hidef]

Re: Tachometer recycling/re-setting

I would suspect the voltage regulator / rectifier is going bad. As it starts to get hot something is opening up and then closing again. When it does it resets the system check warning lights and tachometer. Before rushing out and buying a new regulator though I would verify the cable from the tach to the engine to make sure everything is good there including the two modular plugs to make sure the connections at the engine and tach are also good?

 

[hydra23]

Re: Tachometer recycling/re-setting

hidef;
Thank you for your response. I forgot to mention that only the lights recycle, the RPM`s reading is stady and the needle does not drop to zero. Im ready to conduct a second test following Joe Reeves method on how to test the reg/rec.
H

 

[oldrudedude]

Re: Tachometer recycling/re-setting

I have had the experience of having one of the rectifier diodes fail at higher rpm. This caused the output D/C voltage to fluctuate with A/C impulses and eventually the battery would go dead. Don't know how you would check the diodes at high rpm. The usual method I have used is simply to test continuity through the diode both ways. I suspected something was wrong with the rectifier because at high rpm the D/C voltage reading coming out of the rectifier would jump all over the place. The higher I would rev the more the D/C output dropped. This was tested between the rectifier and the regulator. Maybe you do have a failing rectifier feeding an unstable current through the switch.

 

[Chris1956]

Re: Tachometer recycling/re-setting

Oldrudedude, The voltage regulator he has will not allow you direct access to the diodes, to test as you have outlined. He can check for AC voltage at the battery. If that is found it is very likely the VR is bad....

 

[hydra23]

Re: Tachometer recycling/re-setting

Chris;
Do reg/rec can act this way? Can the rectifier side of the assembly work while the regulator is bad?
H

 

[hydra23]

Re: Tachometer recycling/re-setting

hidef;
Based on your comment, and after the reg/rec gets hot wouldn`t the symptoms be continuos instead of every few minutes at a time? Remember I don`t loose the RPM`s on the tachometer just the 4 lights will briefly illuminate not even in sequence just a brief flash and the alarm will beep very weakly.

 

[oldrudedude]

Re: Tachometer recycling/re-setting

If the reg/rect are integrated, you cannot test the rect alone for output. But you still should be able to test the diodes at the plug where the A/C enters from the stator. ....... sorry I'm mistaken.

12.7v seems a little low. Isn't voltage usually clipped around 13.5v?

hydra, try to do a voltage reading of the power from the ignition switch right at the tach. Voltage there may be dropping just enough to trigger the recycle.

 

[hidef]

Re: Tachometer recycling/re-setting

Electronic issues and heat can drive you crazy. You have an intermittent issue where something is opening up when it gets hot and it stays opened until it cools down. This makes it harder to troubleshoot because it doesn't kill the engine. Generally if you get a short in the electrical system it will kill the engine. I suspect it is in your regulator but it is hard to tell. Are you using a separate tach and system check gauge or the tach with the built in system check warning lights?

 

[hydra23]

Re: Tachometer recycling/re-setting

Guys;
Thank you for your interest. I don`t have a separate tachometer. Tommorow I`m taking the kids for a spin, I will bring my multi-meter tester and probe around at different rpm`s. A few days back I let the engine run on muffs for about 20 minutes during that time the reg/rec was cold to the touch and voltage was around 13.50 @ 900-1000 rmp`s. No recylcing there it only happens at above 4,000 rpm`s. Or maybe a loose connection? that happens while underway. I`m running out of ideas....
H