Use a multimeter and check that you have signal in the gray lead as well as 12V and ground.
getting 12 volts at the ign post and reading 10.5 volts at the send post. The tach needle goes to O when power is introduced. What I am curious about is the wiring on the block on the engine. The teleflex instruction is showing that my gray wire (tach) should be coming out of my throttle unit.