I changed my fuel pump with a used one which fixed the problem of having to turn the key twice to start it, but now my fuel gauge is acting weird. From what I can figure out, when my fuel level is between full and 1/2 tank, the gauge reads full. Once the actual tank falls bellow half a tank, the gauge starts working normally from full-1/2. It's almost like the problem is that the float is not calibrated and the float has the wrong zero-point for empty.

 

Sounds like you got a bum pump to begin with.

Baring nothing hanging up the float itself.

 

I've had my truck since 2006 and I go 200 miles from full to half on the gauge and only a 100 more from half full to empty.
I just live with it.

 

Mine does not move at all for the first half of the tank, it stays on full. When the gauge reads 1/2 tank, I am out of gas.

 

Why was it used before, who did you get it from, and did they say there were any problems with it before.

Even if they said there were no problems with it before, they might have been not so gentle pulling it out. Put a new pump in, but before you dump it in, connect it to the harness, have your significant other watch the guage and you manually move the float, esentially checking range of motion and reporting back to the guage.

 

Float arm is very easy to bend/tweak.