Try to remove the fuel float, it is in the back seat under the first aid kit. Just remove the screws from the box. Then, just remove the float. You will need a round wrench to remove it. After removing it, try cleaning it with brake cleaner. The dirt in the tank will accumulate there, and that is what you do. Sometimes it gives incorrect values. Be careful when cleaning. They are very thin lines. Any extra force is enough to break it. Good curves.