New Fuel Sender Question.....

[Dennis Detweiler]

I put a new tank and fuel sending unit in in my 39 Plymouth.  Before I put gas in it, I hooked up the battery and the fuel gauge went to full. So, I reversed the wires on the sender and it went back to empty. Then, I put 10 gallons of gas in the tank and the gauge needle moves from far left up to slightly past empty. When I turn the ignition switch off it bumps up a little then goes back to far left. With 10 gallons in it, the guage should read at least half full?

Edited September 27, 2018 by Dennis Detweiler
more info

[TodFitch]

I think 1939 was the first year for the two wire fuel gauge used through 1948. It takes a different type of sending unit that earlier or later cars, did you get the correct sender?

[knuckleharley]

14 minutes ago, TodFitch said:

I think 1939 was the first year for the two wire fuel gauge used through 1948. It takes a different type of sending unit that earlier or later cars, did you get the correct sender?

Thanks,Tod. I had no idea.

[Dennis Detweiler]

Yes, it's a two wire plus I grounded the sender to the frame.

Edited September 27, 2018 by Dennis Detweiler
added info

[Plymouthy Adams]

a to a     b to b....be sure there is continuity on these wires gauge to sender....be sure you have the voltage supplied to the gauge.....the gauge also has a built in 5 volt regulator...

[Dennis Detweiler]

The whole car has been rewired and schematic made in the process. I've been on-line finding info on the guage. I looked at my wiring schematic and I did replace the three wires from the guage. It's a pretty simple wiring project, so I doubt anything is lacking continuity. Since the guage went to full on an empty tank and I switched the wires around, it should be showing at least an approximate half tank of fuel after I put in 10 gallons. I'm guessing the resistor or points aren't functioning on one side of the guage. As luck would have it (not that often), I found a NOS 39 guage still in the box on ebay. So, I bought it.