Evidently the clip for the ground circuit at the gauge wasn't contacting correctly and was arcing. The printed circuit board was discolored and peeling around the connection. I cleaned off a spot and soldered a wire from the clip to the board and it worked fine.
It had another problem running hot.....I thought. Come to find out the temp gauge is off too. It shows 230-260* when it's actually running 190-210*. I put a mechanical gauge in to remedy that. The voltmeter is also inaccurate, it shows ~16 volts when it's actually 13.8-14v.