[DanEC]

I haven't made note of any increased swing in mine under 1/2 tank but I have a fairly late car so maybe there was some subtle change in the tank or the fuel level sender. Or maybe I just never noticed. If your gage doesn't read full when the tank is full, that is almost always the sender in the tank. It probably isn't positioned correctly and the float isn't moving the rheostat to the lowest resistance (could be highest - can't remember w/o checking) to signal the gage to read full. They can be adjusted but it usually involves draining the tank down and opening it up to pull the float out.