Re: Evinrude 1977 55hp - tacho wiring
Inductive pick-up car tachs will work. Doesn't matter which plug wire you attach to. Since they fire differently, a 2-stroke will show double RPMs. So if it reads 3000, the motor is running 1500. Problem might be the scale. 5,500 RPMs doubled will be 11,000 on a car tach. Might not have enough digits on a digital, or enough sweep on an analog.<br /><br />Outboard tachometers work off the alternator. The wiring is different. Black is -, purple is keyed +, blue is the backlight, and gray is the signal. The gray wire attaches to one of the yellow alternator wires to provide the signal. That signal would be meaningless to a car tach.