One other possibility to be aware of, as this happened to me. I also had a new replacement fuel level sensor, but discovered they aren't that well made and the possibility exists for the body of the sending unit to ground out on the gas tank. I discovered this while I was troubleshooting and loosened the screws holding the sending unit, which resulted in the gauge working correctly. If I remember, all I did was be careful about centering the sending unit in the hole while tightening the screws, ensuring it didn't touch the tank.
