need a replacement tachometer

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Jan 8, 2009
33
Oday 272 Monmouth Boat Club Red Bank NJ
Has any one attempted to replace there Oday motorola tachometer. I have a 1987 tach that reads incorrectly.
Charlie D
 
Nov 3, 2010
564
Oday 39 Lake mills WI
Generally, the reading on the Tach has more to do with the alternator and the pulleys on the engine/alternator. Replacing the tack is very easy but will likely give you the same reading.
On my boat, the alternator sends a signal (electrical) to the tack. You may want to check if your alternator is driven to slowly or to fast. That's very important.
 
Dec 27, 2011
279
Oday 272 Pensacola
My '87 272 also has a Tach problem. Idling it shows about 200-300 RPM. Under (what I consider) normal load, it drops to zero. Never have been an inboard fan, so am used to 'normal' operation sounds from outboard, and decided that Tach is relatively useless anyway (for me). Never run it 'wide open'. Idles well, so no real problems that are RPM related... Also have a small volt meter problem. Manual says at rest w/key on, volt meter should show voltage of battery. Running at speed should see increased voltage. Mine says 12 volts all the time. Haven't taken the time to check wiring, but looks like wiring of others with same model/panel. Guess I should be checking connections, but haven't done that either. Only had boat 2 yrs...

Charles
 
May 30, 2006
354
Oday 34 Chesapeake Bay
cbourne200,

sounds to me like your alternator has an issue and is not providing any output. Suggest that you put a voltmeter across your batteries to see if you have a voltage increase from not running to running. If there is, then perhaps the wiring is shared between the voltmeter and tach and is faulty.

Charlie D, that may be your issue as well.
 
Jan 8, 2009
33
Oday 272 Monmouth Boat Club Red Bank NJ
Your problem sounds exactly like mine. Except that I do not get any reading on the tach at idle. I need to rev up the engine speed to get a reading. Of which the tach reads low and inaccurate. Do you know if a deep cell battery will read any different than a starting battery? I have two deep cell batteries that take forever to charge.???
 
Nov 3, 2010
564
Oday 39 Lake mills WI
Your problem sounds exactly like mine. Except that I do not get any reading on the tach at idle. I need to rev up the engine speed to get a reading. Of which the tach reads low and inaccurate. Do you know if a deep cell battery will read any different than a starting battery? I have two deep cell batteries that take forever to charge.???
Don Casey has several books out on marine electrical systems. You can also count on your local auto mechanic as marine alternators function the same as auto alternators. I suggest you by someone a beer. It will save you a lot of time and frustration. One quick lesson and you will see that they are rather simple.
Also check ARCO starting and Charging specialists are a good resource. www.acromarine.com they have phone help that may give you a good start.
 
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