What was found
SHORTLY AFTER RUNNING THE CENTER TANK DRY AND SECURING THE CTR TANK FUEL PUMPS, THE MAIN TANK 2 FUEL QTY INDICATION RAPIDLY DROPPED APPROXIMATELY 2000LBS. WHILE WORKING THROUGH A POSSIBLE FUEL LEAK SCENARIO, THE MAIN TANK 2 INDICATION FLUCTUATED UP AND DOWN 1000-2000 LBS. THREE MORE TIMES. FUEL USED AND ALL ENGINE INDICATIONS REMAINED NORMAL. GROUNDED - YES. REMOVED AND REPLACED PROBES TU1, TU9, TU2, TU3, TU4, TU5, TU12, TU10, TU11, TU6, TU7, TU8. ALL PROBES REPLACED REF B737-900 AMM 28-41-00. #2 FQIS TEST GOOD REF AMM 28-41-00. ALL CIRCUIT BREAKERS FOR FQIS ARE RESET.