Tachometer inconsistent reading

seavee capt

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Jan 13, 2012
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I've been getting an inconsistent reading from my Yanmar tach which is connected to a 4lha engine. Any thoughts on where to look first? Grounding, sending unit and tach cable have been what I would think, but I haven't yet looked under the proverbial hood yet.
 

Toro

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check all pins on the engine end of the tach wire first.
 

Pedlyr

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Many tachs have a little dial type reostat in the back. You set them to your engine with a little screw driver until you get the proper detente. Sometimes they can get corroded. Just dial it around a few times with the screw driver and return it to the original position.

It could even be in the wrong detente position if it never worked right.
 

captainlarry84

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KristenFormer Charter Captain
On the starboard side of the motor is the sender. It reads off of the flywheel. Find the sender down very low. Clean both the contacts & you should be fine. It is an easy fix and a common problem.
 
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