What was found
(CAN) DURING A ONE HOUR FLIGHT, THE FUEL QUANTITY INDICATION WAS OBSERVED AT 1/2 TANK, MOVING TO ALMOST EMPTY INDICATION. PILOT DECLARED AN EMERGENCY AND FLEW TO PUEBLO. AFTER LANDING, FUEL INDICATION WAS OBSERVED AT 1/8 TANK. SENDING UNIT WAS REMOVED AND CLEANED, REINSTALLED, CALIBRATED. AIRCRAFT RETURNED TO SERVICE.