tach wiring

[dirtdemon]

i have a 1975 model evinrude 85 horse that im tryin to put a tach on, the wiring horness does not have a grey wire comin from the control box, so i ran a wire to the bus bar that was marked grey and according to the manual thats the tach wire, it still doesnt work, now with that being said theres a post on the back of the tach that says send unit when i hook a wire from a primary power source to that post the tach works but is very inaccurate, where am i going wrong, the tach is also set on 4cyl. 2 pulses thats the only setting for a 4 cyl. motor

[dirtdemon]

[rickdb1]

Gray wire goes to the send (S) terminal, hot wire (Ignition) goes to the "I" terminal and a ground wire to the "G" terminal. I can't say if the Tach you have is compatable with your motor though.

[dirtdemon]

thanks i will try that