I have a 98 evinrude 225 carburated. i started the motor up yesterdayand looked at my tach and it said the motor was turning 2200 rpms at idle. the motor was not reved up at all it was idling just like normal. coulld the tach be going bad or already gone? or is there anything in the motor that could cause it to sentd the wrong numbers to the tach. my tach is just an old analog gaffrig gauge.
any help is appreciated.
Tachometers usually have a selector switch for calibration of the tachometer to the engine's pulse rate, and sometimes the switch contacts become corroded. I recommend you check the tachometer first to see if it is the source of the error. The procedure is
--make a note of the current setting of the calibration control
--using an appropriately sized screwdriver, move the calibration control back and forth throughout its range; this will cause the switch contacts to be wiped clean and should restore them
--return the calibration control to its original setting
I have seen this procedure solve problems on several boats where the tachometer readings were suddenly out of calibration.
If you have a digital multimeter that includes a frequency measurement function, let me know and I will describe how you can use it to check the tachometer signal frequency.
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