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Does anyone know the correct ohms at empty and full that the gas tank sending unit should produce to correctly put the fuel gauge at empty and full. I currently get 6.5 ohms at empty and 44 ohms at full. This only puts the gauge between 1/4 and 3/4. This would be on a 1937 Super Eight. Thanks

If no one else has the info, as a suggestion you might see if KM Lifestyle would have the info and more importantly if they would share it. Since they are in the business of repro'ing or repairing senders they might want to keep it a secret.mykmlifestyle.com/KM_Lifestyle_Fuel_Senders.html

From the info on their website it appears Packard could have used one of 3 different brands in their fuel gauges and senders in 37 so the resistance value would probably depend on what unit is in the car. They have photos of the various senders so that might help narrow it down.

One of the brand gauges used was Stewart-Warner and I know one of their obsolete resistance ranges was 0 empty 100 full. I believe most if not all Clippers thru 47 used that brand and range but S-W might also have had other obsolete ranges before they settled on the current 240-33. Other brand gauges could be completely different. If you cannot find the info any other way, providing your gauge is working you can get a potentiometer such as this one and experiment to find what will give you a proper reading. 100 ohms max in the pot should be enough range if the gauge is reading a rough average half scale at 44 ohms but not knowing which brand gauge is in the car I can't promise it will be.

Connect one end terminal of the pot to ground and the center wiper terminal to the gauge wire and turn the pot until the gauge reads full. Disconnect the wiring and measure the resistance in the pot between the two terminals you used and that should give you a reasonably accurate number the sender would need.