Tried to calibrate the fuel tanks. Despite progressively adding in fuel the ohm reading at the sender site nor the voltage as read on the PFD did not change. I placed up to 25 gallons in the wings, rocked the wings thinking the sender float was stuck and no change. After consultation with Stewart Warner the makers of the fuel sender and Aerotronics, Jim Dobbens inspecting the readings and indications on the PFD, collectively we decided the fuel sender unit was constructed incorrectly. We theorized I neglected to put the last 90 bend in the end of the float rod that secures the float to the sender body. I opended the inspection panels to remove the bolts aft of the main spar that hold the tank, removed the screws on the tank skin and removed the tank for inspection of the sender units.
