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Author Topic:   Tachometer on 2004 MONTAUK 170
Marsh posted 06-21-2004 06:11 AM ET (US)   Profile for Marsh   Send Email to Marsh  
The tachometer on my 2004 Montauk 170 with 90-HP Mercury four-stroke never falls below an indication of 1000 RPM, even with the engine turned off. I don't hear as well as I used to. Around a noisy launch area, when I first crank up the engine, I often look at my tach to see if it's is running (the 4 strokes are quiet, but not THAT's my hearing!)

Problem is, even with the engine turned off, tach still reads 1000. I would expect it to read zero. It has been this way since I bought the boat new last January.

Any thoughts?


davej14 posted 06-21-2004 07:38 AM ET (US)     Profile for davej14  Send Email to davej14     
I have a 2000 75 2-stroke Merc. After shutting off the motor the tach stays at 1,000 RPM until I move the switch back to "on" (not cranking the motor, just on) at which point the tach goes to 0 RPM and stays at 0 RPM when I move the switch back to "off". It will be interesting to see what others have experienced.
gimcrack225 posted 06-21-2004 07:55 AM ET (US)     Profile for gimcrack225    
My OMC gauges do the same thing.
jimh posted 06-21-2004 08:29 AM ET (US)     Profile for jimh  Send Email to jimh     
Almost every tachometer gauge I have seen has had an offset as described above. With no power they read about 1000, and settle to 0 with the engine off but with power applied to the gauge.

If you have a water pressure gauge (which I recommend), it might help you interpret the engine's ON/OFF state better in that situation.

AQUANUT posted 06-21-2004 10:19 AM ET (US)     Profile for AQUANUT  Send Email to AQUANUT     
the tach is functioning properly

however, the rpm at 1000 is too high...will look it up book chapter and verse today...I am thinking ball park of 750-850rpm
will advise if ya like later

divefan posted 06-21-2004 02:53 PM ET (US)     Profile for divefan  Send Email to divefan     
Mine does the same thing.
BemidjiWhaler posted 06-21-2004 05:06 PM ET (US)     Profile for BemidjiWhaler  Send Email to BemidjiWhaler     
My 2003 Montauk 170 with 90 2-stroke tachometer does the same as davej14 and jimh mentioned. When initialy turned off the tach stays around 1,000 RPMs. When power is applied to the ignition, but the engine is not started, the tachometer falls to 0.

I just returned from the garage after having a beer while conducting the "power on" test. If anyone questions the test results, I will gladly return to the garage and repeat the entire process.


Marlin posted 06-21-2004 06:01 PM ET (US)     Profile for Marlin  Send Email to Marlin     

When conducting serious testing, one should repeat the test to make sure the results are consistent. I prefer conducting an odd number of tests so there's always a tie-breaker.

Please return to the garage and repeat the entire procedure at least two more times.


dgp posted 06-21-2004 07:33 PM ET (US)     Profile for dgp  Send Email to dgp     
My Mercury (Teleflex) brand tach, vintage year 2000, always returns to 1500 RPM after shutdown. Most mfrs use an orientation magnet that returns the pointer on gauges to the same position when power is removed.
davej14 posted 06-21-2004 10:34 PM ET (US)     Profile for davej14  Send Email to davej14     
This sounds like a bad design to me. When the engine is off the tach should obviously read "0" no mater what the marketing guys say. They probably saved the cost of a 2 cent bleeder resistor or diode.
Marsh posted 06-22-2004 05:30 PM ET (US)     Profile for Marsh  Send Email to Marsh     
I think you guys are correct. But, just to be sure, I just remembered that I, too, have a few beers in the garage fridge, and just might have to do the reproducability/repeatabaility study a few times, as Dave described above!


Marsh posted 06-24-2004 05:05 PM ET (US)     Profile for Marsh  Send Email to Marsh     
Yup (burp) guys are right...(burp)...better go check it one more time, though.


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