I have a 1998 dodge neon, automatic the fuel pump failed so I replaced it, now the fuel gauge seems to be acting strangely, I filled the car yesterday and showing 18 miles on the odometer it is showing a half a tank, this is the car I use to go to work so any help is appreciated, also no gas leaks or smell of gas

 

most likely your gauge cluster is going. pull the cluster out of the car. and take the backing off and resolder the points on the circuit board. or you didnt put the sending unit in right when you did the pump