OK, I've been all over trying to sort this tach thing out. The motor is a 1992 Evinrude 40hp (sorry, the boat is in another location, so no further info) and my tach is erratic, jumping all over the dial. I know it could be dangerous (and expensive) if it is the voltage regulator. But, I wiggled the plastic thumb screw setting button on the back of the tach back and forth, and the readings setttled down until I went to full throttle, then they jumped around again.<br />Now, I can't see the back of the tach under that little console due to space and wires under there, and I'd like to avoid pulling the tach out of the dash....so many wires all bundled together.<br />Is is likely that I cleared up some corrosion on the tach by moving that thumb button back and forth and that helped it? And if so, how do I know I left it on the correct ppm since I can't see the back of the tach?<br />What a mess...<br />Jack
