If your careful you can slightly bend the fuel gauge float rod in the fuel tank to make it read more accurate.You would need to bend it down slightly if the gauge reads empty when theres fuel left in the tank still.Or you need to bend it up slightly if the gauge reads that theres fuel left when theres not.Also the fuel pump pickup sits inside a "pot" on the bottom of the tank called the swirl pot,which is where the fuel return line also empties back into the fuel tank.This is so the fuel pump doesnt get starved for fuel when braking ,accelerating and cornering etc when the fuel level is low and the fuel is sloshing around a lot inside the tank..Ive seen a few of these in tank return lines snapped off or not reconencted ,probably from a bodgy mechanic that didnt do the job properly,or some backyarder who couldnt reconnect the return line again, as it can be difficult sometimes to re connect it.So it might be worth checking out too.