It appears I had multiple issues. First I pulled the "new" sending unit to check resistance. It showed a consistent 0-15 with the arm moving from empty to half, but then as I continued to raise it, it started showing very sporadic readings. What I found was the contact in the sending unit was not making positive contact in that range. I removed the cover and bent the contact tab and it now shows a very consistent 0-30 ohms as the arm moves from E to F. The picture shows the tab I had to bend. (Hope that info will help somebody with a bad sending unit.)
The gauge still wasn't working properly so I pulled it out to bench test. I connected 6v to the gauge and connected the sending unit. I grounded the sending unit, but not the gauge and with the sending unit in the empty position (0 ohms) the needle went to about 1/4 tank. As I raised the arm, increasing the ohms to 30, the needle dropped to E (backwards from what was expected). I then grounded both the gauge mount and the sending unit and the needle froze at just above E and would not move regardless of the sending unit position. Regardless of what I did, I could not get the gauge to go above 1/4. I can only deduce that the gauge is fried. This is disappointing because the face and needle are in mint condition.
Does anyone know of a place that will rebuild the gauge?
