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Author Topic:   Does a faulty power pack = a faulty tach

Matt F posted 02-11-2010 05:10 PM ET (US)
Last summer my boat -- powered by a 1998 V4 Johnson looper -- was sidelined with a faulty power pack that was on back order until this week. And, while I am confident the power pack is bad (at least that’s what my mechanic says), I am curious as to whether the problem runs deeper. The reason for this is that my tachometer seemed to act up at around the same time. It would either not work at all or take a while to kick in (almost as if it needed several minutes to “warm up” and register any sort of reading).
Is this explained by the power pack too or does it signal an issue with the regulator/rectifier or perhaps the tach itself.
Thanks for any thoughts. I just want to make sure I deal with whatever needs to be done this winter.
Jeff posted 02-11-2010 08:11 PM ET (US)
It is my understanding that this type of malfunctioning tach is the common symptom of a failing rectifier.
Sal made a good post here that should help you.
http://continuouswave.com/ubb/Forum3/HTML/004717.html
jimh posted 02-11-2010 11:00 PM ET (US)
I believe the tachometer signal on an OMC V4 is derived from the rectifier, not from the Power Pack.
Matt F posted 02-12-2010 08:47 AM ET (US)
Thanks guys — appreciate the help. Sal’s test seems simple enough that even a technophobe like me could give it a go.
The funny thing is that when I was giving this more thought, I realized the system check still works. I guess I thought that it would have been a more black or white issue (that the rectifier either supply power or it doesn’t). I guess I am just continuing to learn that few things are ever as black and white as they would seem...
tom976 posted 02-13-2010 02:00 PM ET (US)
First you lose the tach, then you lose the ability to charge and then the motor doesnt run. Happened allot to the older motors because it didnt get enough cooling water to the underside of it. Basically it overheated. On the 175 that I had, I had to pull the flywheel off and there she was.
fishinchips posted 02-14-2010 02:04 AM ET (US)
I had the same motor like yours on my old boat. The tach will work for a while and then it will peg and then stop working.
Turned out to be the rectifier.
Ken (170 montauk / 22 hydrasports wa)

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Author	Topic: Does a faulty power pack = a faulty tach
Matt F	posted 02-11-2010 05:10 PM ET (US) Last summer my boat -- powered by a 1998 V4 Johnson looper -- was sidelined with a faulty power pack that was on back order until this week. And, while I am confident the power pack is bad (at least that’s what my mechanic says), I am curious as to whether the problem runs deeper. The reason for this is that my tachometer seemed to act up at around the same time. It would either not work at all or take a while to kick in (almost as if it needed several minutes to “warm up” and register any sort of reading). Is this explained by the power pack too or does it signal an issue with the regulator/rectifier or perhaps the tach itself. Thanks for any thoughts. I just want to make sure I deal with whatever needs to be done this winter.
Jeff	posted 02-11-2010 08:11 PM ET (US) It is my understanding that this type of malfunctioning tach is the common symptom of a failing rectifier. Sal made a good post here that should help you. http://continuouswave.com/ubb/Forum3/HTML/004717.html
jimh	posted 02-11-2010 11:00 PM ET (US) I believe the tachometer signal on an OMC V4 is derived from the rectifier, not from the Power Pack.
Matt F	posted 02-12-2010 08:47 AM ET (US) Thanks guys — appreciate the help. Sal’s test seems simple enough that even a technophobe like me could give it a go. The funny thing is that when I was giving this more thought, I realized the system check still works. I guess I thought that it would have been a more black or white issue (that the rectifier either supply power or it doesn’t). I guess I am just continuing to learn that few things are ever as black and white as they would seem...
tom976	posted 02-13-2010 02:00 PM ET (US) First you lose the tach, then you lose the ability to charge and then the motor doesnt run. Happened allot to the older motors because it didnt get enough cooling water to the underside of it. Basically it overheated. On the 175 that I had, I had to pull the flywheel off and there she was.
fishinchips	posted 02-14-2010 02:04 AM ET (US) I had the same motor like yours on my old boat. The tach will work for a while and then it will peg and then stop working. Turned out to be the rectifier. Ken (170 montauk / 22 hydrasports wa)