1998 Jeep Grand Cherokee Fuel Indicator

I have a 1998 Jeep Grand Cherokee Laredo w/ the Up-country suspension. The vehicle has 90K miles and had been stored outside from 2003-2004 without being driven. Since 2004, the vehicle has driven fine.
About two weeks ago the fuel level indicator started showing empty even though there were 7 gallons of fuel remaining in the 23 gallon tank. I replaced the fuel pump/sending unit assembly and the problem still persists. Is there another module involved in measuring the fuel level? Do you know what else it could be aside from the sending unit?