fuel gauge always read ful ,on ,off?

Question

sending unit is new

Answer 1

You've got a broken or cut wire.

Fuel sending units are primarily resistance units.
Low resistance, empty tank = low reading.
High resistance, full tank = high reading.
Broken wire = high resistance = high scale reading.

There are one or two that work the opposite way.

Answer 2

I am not sure what you are asking, but you should be aware there are usually two fuel sensors in each fual tank in a car. One sensor for the top half and one for the bottom half. One of the two sensors failing can cause wierd fuel readings.