91 Merc 90hp 3cyl - High voltage situation and alarm problems

[jpollman]

Hi there,
I'm not new here but it's been a while since I've been around and no matter what I did I couldn't log in so I registered again. Here's the problem.

1991 Merc 90hp 3cyl #0D096992

A month or so ago I was fishing and got a "High voltage" warning on my Humminbird fish finder. I looked over at my voltmeter and it was reading 16 volts. Then I got an overheat alarm. Well I had been trolling for several hours at low speed but I was only a few hundred yards from the launch so I headed in and pulled the boat out of the water. I got home and the next day ordered a new voltage regulator. It came in and I installed it. I had the boat out yesterday with the same result. Within 5-6 minutes of getting underway I noticed the voltage was up near 16V again and I started getting intermittent overheat warnings. Again, I wasn't far from the launch so I headed home again. Now being that I just installed a new regulator, is there anything else that could be causing this high voltage situation? I've already pulled the temp sensor and checked it out. I found that it was open and closed when the temp hit 197 degrees. I cooled the water down and it opened again when the temp hit 177 degrees. (I did this three times in a pan of water on the stove and used my multimeter to check the open/close temps) This seems to be a reasonable operating range to me. How about you? At least it coincides with the specs in my SELOC manual.

Could the high voltage situation be causing my alarm problems?

Thank you very much in advance for ANY input you can give me.

John

 

[Wellcraft 89]

Re: 91 Merc 90hp 3cyl - High voltage situation and alarm problems

Are you sure it's not the low oil alarm ?

Have you chkd your battery connections also for corrosion or loose (the main batt)

Rich

 

[jpollman]

Re: 91 Merc 90hp 3cyl - High voltage situation and alarm problems

Are you sure it's not the low oil alarm ?

Have you chkd your battery connections also for corrosion or loose (the main batt)

Rich

Hi there,
I just cleaned and tightened the battery connections before I took it out so I don't think that's the problem.

I may be wrong but I'm thinking that it's telling me it's an overheat because it's one long high pitched alarm. From anytyhing I've read about it the alarm for low oil is a series of short beeps from the same audible signal. Also, the oil tank is completely full. But then again that doesn't mean there isn't a problem with the sensor. I've got to verify that the low oil warning is a series of short beeps.

Thanks for the suggestions.

Oh yeah by the way. I just came back in from running it in the driveway for about 15 minutes with my new multimeter attached to the battery and running about 1K to 1500 rpms I was registering about 13.2-13.6 volts. I may take it to a local lake in the next couple of days and try again. But every time I actually hit the lake, within 10 minutes it's showing about 16V. :'(

 

[jpollman]

Re: 91 Merc 90hp 3cyl - High voltage situation and alarm problems

Are you sure it's not the low oil alarm ?

Have you chkd your battery connections also for corrosion or loose (the main batt)

Rich

Hi there,
I just cleaned and tightened the battery connections before I took it out so I don't think that's the problem.

I may be wrong but I'm thinking that it's telling me it's an overheat because it's one long high pitched alarm. From anytyhing I've read about it the alarm for low oil is a series of short beeps from the same audible signal. Also, the oil tank is completely full. But then again that doesn't mean there isn't a problem with the sensor. I've got to verify that the low oil warning is a series of short beeps.

Thanks for the suggestions.

Oh yeah by the way. I just came back in from running it in the driveway for about 15 minutes with my new multimeter attached to the battery and running about 1K to 1500 rpms I was registering about 13.2-13.6 volts. I may take it to a local lake in the next couple of days and try again. But every time I actually hit the lake, within 10 minutes it's showing about 16V. :'(

Any other ideas folks?

I just got a factory service manual so I've got good documentation. When I run the motor on muffs in the driveway if I get it up near 2k rpms it's showing 16.5V on a voltemeter attached to the battery as well as my voltmeter in the dash. I called the place that sold me a CDI voltage regulator and he told me that possibly my battery was sulfated and that could be causing the problem. But I don't believe that because it's a one year old Optima yellow top and I highly doubt that it's sulfated. I started it up again and used jumper cables to connect a second known good battery (on recommendation of the tech service person) and it didn't change. Still 16.5V. I shut down and am going back to square one.

I'm stumped at this point. :'(

Thanks for any input you may have.

John