While changing the unit will give you 0% which is actually nearer the bottom of the tank this also increases the chances of running the pump dry without increasing your range. Reset the trip and know that you can do around 200 miles between fills. The risk of lowering the level in the tank by using a longer sender is that you might run the tank dry if the car is parked at an angle on a slope and the fuel runs out of the right tank (with the pump and sender) into the left tank. Just a thought
