I just installed a Summit Racing 2 1/16 tachometer on my 1987 Ford EFI 300/C-6 that I have owned for about 8 years. All of the wires are soldered and installed correctly per the instructions.

The tach. does work, but the signal is pulsing (it always pulses higher than the actual engine rpm). The higher the rpms the worse the needle jumps around. At idle the needle does not pulse.

What is my problem?

 

I would get a voltmeter, and check your power connections when you rev the motor. Make sure you put the meter on the ground wire of the tach, and then check both power wires (red and orange) coming in to make sure it's steady.

 

Franklin2 how many volts should I be seeing? 12 volts?

 

12 volts or possibly a little higher.