I have a 03 Neon that the fuel gauge is only reading about half the tank. It shows empty, but will only take 5-6 gallons. I think its the sending unit, but all the local part stores have is the hole pump assembly. Does anyone know where I can buy just the sending unit.

 

Junkyard. Its all one unit.

 

If you have access to a decade box, you can check the guage. The resistance is 0 to 100 ohms, full range. The resistance of the sending unit will also be 0 to 100 ohms, between the stops. Replacing the sending unit can be tricky because you cannot calibrate it to the proper datums.