fuel gauge

[mehoff400]

so i have been messing with my fuel gauge lately trying to get it to work. when i first go the truck i replaced the sending unit it still didnt work but i moved onto other things. i just replaced the gauge with another gauge i acquired and not sure if its working correctly

when i remove the ground from the sending unit with power on the needle doesn't move
when i remove the wire to the sending unit to gauge it goes to full.

from my understanding when i remove the ground it should go to empty.