Inconsistent voltage, Not very electrifying Options

[iankarr]

Hi Guys,

Trying to sort through a puzzling situation. My car started bucking like a bronco(D-jet) and I noticed that the voltage was super low (like 10). I fortunately made it home. Changed out the voltage regulator with one I had in my bin and everything seemed to be fine. 13.5 when running, no more bucking.

Now I'm seeing that the voltage is inconsistent again. Sometimes it's 13.5 when running, then it dips to around 12, then comes back up. Occasionally the red light will come on for a few seconds, even when running at 3K rpm. When I put the headlights on, the idle drops by 500rpm and stumbles.

The belt is tight and the alternator was (supposedly) rebuilt recently.

Anyway...my thinking is it can only be one of four things:

– Bulb in the cluster (unlikely, but possible). I believe it's stock.

– Voltage regulator

– Alternator

– Battery

Do you guys have any simple tests i can run to eliminate any of the above before I just start throwing parts at this? Other thoughts?

Thanks!