Tachometer

[Weasel]

Have had some problems with the tach for a couple of weeks now and would like to see if any of any of y'all out there have any suggestions.
Tach would show engine revs when engine starts but drop to zero while motoring out of the channel, and would occasionally indicate but was erratic. Yesterday it never registered at all. Tapped on gauge and nothing. Motored for 2.5 hours, (no wind), tach needle never moved. Fresh water boat, no salt ever, 250 hours on Yanmar 3G30F engine. Engine is ok. Thanks to all of you in advance for suggestions.

 

[Claude L.-Auger]

Looks like you have a faulty connection. Check & Clean connections on tach itself, then go to the plastic connector that leads to the transmission. On my 3GM30F the pick-up for the tach is on the tranny and the wires go to that connector. When I had the same problem you describe, disconecting that connector, cleaning reconnecting was the solution. After seeing the tach work again, I simply taped the connector to prevent engine vibration when running from getting it loose.

 

[BioAndy]

I recently had a similar issue with my older Westerbeke engine. Tach registered upon startup, but needle jumped around afterward when running. Turned out to be a bad/fatiqued wire connection at the engine alternator. Hopefully, yours is that simple!
Andy