Tachometer issues

Howdy folks -
I have an electronic tachometer on my Yanmar 6LPA-STP - the other day it started to read double of what the engine is running.

I checked all the connections and they are tight - I figured I would ask you folks for any insight before I replace it.

Thanks,
-Sandy

Are ALL the connections also clean? If not both clean and tight the meter may not be able to read the signal.
Are the crimps also good, same as above.

Do not just assume it is the tach.

Thanks for the response C Letric - I'll take a closer look before replacement.

-Sandy

Thanks for the response C Letric - I'll take a closer look before replacement.

-Sandy

The tach on my 6LYA was acting up... eratic and sometime nothing. The terminals on the sending unit on bell housing were the culprit. Cleaned and added conducting grease and problem solved. I dont think that will cause double though.
The yan sender may be at fault.
I have seen a procedure to remove & clean the sending unit. Worth looking up before you pull sender as there was a first step to determine spacing before removal to be able to replicate. I believe you had to screw it in to just touch stationary flywheel and recored # turns or angles so when replacing you turned it in to just touch and back it off the turns previously recorded.

Try to bring a ground connection from somewhere close by to the meter!

Thanks again guys I really appreciate your advice. It's supposed to rain Sunday so I'll dig a bit deeper into the connections.

Funny thing, I went out for a short cruise on Wednesday and the tach was reading correctly Thanks again,

-Sandy

Sunshine said:

Thanks again guys I really appreciate your advice. It's supposed to rain Sunday so I'll dig a bit deeper into the connections.

Funny thing, I went out for a short cruise on Wednesday and the tach was reading correctly Thanks again,

-Sandy

Click to expand...

not sure what tach you have on that, but if it acts up again, look at the back of it and see if there's a little rotary switch on it to help scale it.
i have an alternator driven tach on my sailboat that reads erratically now and then. the manufacturer (teleflex i think) recommends rotating the switch now and then to clean the contacts. just note the position before turning it.

Reading through a similar thread several weeks ago - with interest due to a similar problem I was having with one out of four tachs; go figure - someone asked the OP if the problem occurred while connected to shore power. OP's answer was "yes." Suggested he try divorced from SP. Problem cleared.

I did the same trial and - voila! - tach read correctly. I forget the explanation, but worth a try.