Tachometer not working on Yanmar 2GM20F

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May 24, 2004
470
Hunter 33.5 Portsmouth, RI
A friend of mine has the same Yanmar 2GM20F diesel engine that I have and his Tachometer has stopped working. Any suggestions of what to check first & next? Any input would be helpful. Thanks
 
May 20, 2004
151
C&C 26 Ghost Lake, Alberta
Tach

I've got a 2GM20F in my C&C 26.
When mine stopped working it turned out to be a bad connection.
The tach picks up the revs from the flywheel housing on the back of the engine.
Check that the wire hasn't become disconnected.
sam :)
 
Mar 22, 2004
733
Hunter 30 Vero Beach
Clean the connections on the sender and crimp them down a little on the female ends. slide them back together and it should work. I just fixed mine yesterday, and it now works. It hasn't worked for five years. The sender is on top of the flywheel housing on the right side of the motor if it's like mine. There's two wires.

Dave
 

RichH

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Feb 14, 2005
4,773
Tayana 37 cutter; I20/M20 SCOWS Worton Creek, MD
Most common reason for a Yanmar Tachometer not working is corrosion of the pointer bearings. With the 'ignition switch' in the 'on' position and the engine running at well above idle speed, 'rap' the rim of the tacho with a hard plastic item - usually moves the tacho needle sufficient for it to move to the correct position. If not, then look for electrical issues. This has been a problem with stock Yanmar Tachometers since the early 1980s and continues through the present day.
 

zeehag

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Mar 26, 2009
3,198
1976 formosa 41 yankee clipper santa barbara. ca.(not there)
with my 2qm20h, my tachometer i had installed by the dealer i know didnt work from day one---turned out to be the tach---i got anew one.....
 

Benny

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Sep 27, 2008
1,149
Hunter 320 Tampa, FL
They do go bad; check all the connections and clean the sensor and if it does not work get a new one.
 
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