Installed new coil, now the tach acts funny

I double checked the wires, tach is wired to the negative coil terminal. Ground looks good.

pntastar69 said

Did you reinstall the original coil to see if the results are the same?

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Just tried that, same problem. So that tells me that it’s not the coil, rather something with the tach. Which is weird, because I didn’t do anything to the tach besides disconnect it from the coil.