Here is what I have done so far during troubleshooting this prob. 1) grounded the sending unit wire, gauge moves up to 'H' (means the gauge should be good) 2) replaced sending unit with a new unit, gauge does not move?? 3) connected my orig sending unit to the sending unit wire and grounded the threads of the unit. Then heated up the sending unit, gauge registered/moved accordingly towards 'H' ! Why doesn't the gauge work with the original sending unit installed in the manifold?? Could the gauge still be bad even though it moves when grounding the sending unit? Not sure if it is related but my gas gauge reads empty. I will try grounding its sending unit wire as well....any help would be appreciated.