Speedster Tachometer Signal Issue

[etemplet]

Having a few electrical issues on the Speedster. Port tach reads above 4000 RPM but not below. I swapped the tach input with the starboard engine and the port tach reads properly. I'm guessing it a signal problem. Looking at the wiring diagram I see a 20k resistor in the line that comes directly off the mag. Could the resistor be faulty? I get good readings above 4k rpm. I'm going to check the mag plug to make sure I'm getting good contact. Help is appreciated.

 

[etemplet]

I checked the 20K resistor and it's reading properly. I'm not wondering if the rectifier could be the culprit. I have a whole nuther gray box for the Speedster. I might just swap out the rectifier and the resistor for good measure. The only other issue would be the wire going up front to the gauge and looks like a straight run up to the storage compartment. I can't see many places for the problem to hide.

 

[etemplet]

I cleaned the mag plug, reposition the wires, and cleaned the plugs under the tach in the front compartment. To my surprise the port tach came alive !! Yipppeee !!!
The only thing I don't have working correctly is the speedometer.