Correct Tacho for 1982 Evinrude 70hp?

[driver440]

I have a dead tacho on a newly acquired boat with a 1982 3 cylinder Evinrude 70hp. The tacho needle is frozen at the 2750 rpm mark whether the engine/ignition is on or off.<br /><br />The tacho is made by quicksilver and has a range selector as follows:<br /><br />1= 4 Cyl 4 Cycle<br />2= 6 Cyl 4 Cycle<br />3= 8 Cyl 4 Cycle<br />4= 12Pole Alter <==== Tacho is set to this<br /><br />There isn't a 3 Cyl 2 Cycle setting so I'm wondering if this was the original equipment and whether the range selector was set correctly? <br /><br />If this is a suitable tacho, correctly set, is there anything I can do to breath life into it ?<br />If I need a new one, is there a particular one I should be looking out for?<br /><br />Appreciate some guidance from those that know.

 

[angus63]

Re: Correct Tacho for 1982 Evinrude 70hp?

Pretty certain you have a 12 pole / 6 pulse motor<br />Looks like position 4 is correct. Have you removed and cleaned all of the connections? Is your charging system working (14+ VDC when running)?

 

[driver440]

Re: Correct Tacho for 1982 Evinrude 70hp?

The Tacho shows 2750 rpm when it is completely removed from all wiring so I suspect it isn't a case of dirty contacts.<br /><br />Should I look for another Tacho with the same range settings or should there be one that specifically covers 3 Cyl 2-stroke? Any other thoughts?

 

[angus63]

Re: Correct Tacho for 1982 Evinrude 70hp?

Where the needle sits when no power is applied differs from tach to tach (mine is about 1200 rpm). Clean and tighten the connections and see if it works now. If not, check with a meter across the battery terminals to see if you are charging when running (14 VDC+).<br />It may be your rectifier and not the tach that is bad.<br />Good luck<br />Edit: Also check that you have 12V + to the tach when you turn the key, and that you have a good ground.