Re: Tachometer

Eric Freedman

Your hull number is very close to mine. There is a sender on the outboard side of the engine about one third of the way down on the bell housing.

It is almost directly above the flywheel ; it has a big diameter and 2 wires with push on terminals. I would start by cleaning the studs of the sender and the solderless connectors and then use Corrosion-x. 


If you do not have that sender there should be a wire hanging off the side of the 12v alternator.

That is the tachometer lead if you do not have the sender above the flywheel there should be a wire attached to it.

If the alternator is the source of the RPM’s go to an auto alternator shop. If they must replace the entire unit , make sure it is an isolated ground model.


However, my first guess is the tachometer itself. I recall having that problem on a 4jh2e Yanmar years ago.

Fair Winds


Kimberlite Amel Super Maramu #376



From: On Behalf Of Steve Bell
Sent: Friday, June 03, 2022 12:20 PM
Subject: [AmelYachtOwners] Tachometer


Hi All,
         The rev counter for my Yanmar 4jh3-hte on my gauge is fluctuating the higher the revs the less fluctuation.
I don't believe the tachometer is working correctly .
Where is the tachometer sensor on the engine? or where does the rev counter get its input from and how can I check this.?

e.g the rev counter will show 1200 rpm and then jump to 1400rpm with no increase in engine revs or bounce between 1500 rpm and 1600rpm 


s/v Dusk # 378

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