I'm going to have to disagree with Hot Rod Dad. The 30 ohm sending unit hole spacing is not the same for all of the fasteners. The sending unit will only go in one way. By appearance they look the same but they aren't. There's enough difference to keep you from getting it in wrong. A 6" scale and two minutes measuring will prove it.

I guess the first thing I would check is the ohm range the sending unit shows from the empty position to the full position. It should read close to 0 @ empty and close to 30 ohms @ the full position. If that reads correct and you have a 30 ohm gauge that you know works check your wiring again. Good luck.

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