Fuel gauge will not read full?

After I installed a new fuel pump and sending unit, my fuel guage will only go to 7/8 full. The original sending unit when the car was brand new would send the fuel guage well passed the full line?
Any help or suggesting would be grealty appreciated.
Its a XE v-6 70,000 miles

I'm not sure if it has to do with your install. I know of several trucks (mine included) that don't read "full" after a stop at the gas station. If mine does read full, then when my gas light turns on I have almost no gas left compared to those who's gauges read normal.