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RPM gauge fluctuates wildly

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Amanda Thayer

New member
My RPM meter seems to not be reflecting the actual rpm's the motor is generating. I will be motoring along at 3000 for 10-15 minutes with no problem. I look at the meter and suddenly it is showing 5000. If I flick the meter with fingernail a couple of times it will drop back down to the 3000 mark. This happens at various speeds with no discernable pattern. Bad meter? Wiring issues? New boat?
Amanda
 
There should be a switch on the back of the tach. Note the position and switch it through al the settings a few times and then return it to the original position. If that cures the problem plan on replacing the tach in the near future. Moisture makes its way to the contacts and once inside the tachs days are numbered. Be sure and disconnect the battery before messing with any of the wiring connections especially under the dash.
 
kimcrwbr1 said:
There should be a switch on the back of the tach. Note the position and switch it through al the settings a few times and then return it to the original position. If that cures the problem plan on replacing the tach in the near future. Moisture makes its way to the contacts and once inside the tachs days are numbered. Be sure and disconnect the battery before messing with any of the wiring connections especially under the dash.
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Thank you!
Amanda
 
That engine is one of the ones that had a recall for the bad regulator/rectifier, I think. You may be entitled to some testing and a replacement at the dealer, since the rec/reg was known to start fires when it went. I have a neighbor who had one he bought new in 2005, on a pontoon boat. The regulator melted down and caught the engine on fire here in the last couple months, because of a bad regulator/rectifier. They saved the boat but the engine was a mess, he just sold the whole thing. Mercury said "too bad, so sad, you should have brought it in before the fire." He had missed or ignored the recall notice, which they would have honored prior to the fire, even in 2016. It may be something you want to check on with your motor, which is acting like the regulator/rectifier is failing.
 
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