OK,
Let's say the sending unit is working. When you bought this gas gauge, did it say what resistance of sending unit it was matched to? This could be for a Ford or GM car if that wasn't stated. We do know the gauge works at this point, the problem now is knowing if it can read what the sending unit is "saying". I don't know if I'm making sense to you or not, but it is clear in my head. :laughing:
Mike