What was found
ATB, EMERGENCY DECLARED, FUEL IMBALANCE 2-3 EICAS ADVISORY MSG ON DEPARTURE. MAXIMUM IMBALANCE REACHED 16,000 LBS WITHIN ABOUT 40 MIUNUTES. TANK 2 WAS LOW TANK. RESULTED IN AIR TURN BACK. REF. TECH ALERT ON MAINTENIX BARCODE T3F1800747A8, REPLACED NR 3 FWD OVERRIDE PUMP IAW AMM 28-31-01, GROUND OPS AND LEAK CHECK GOOD. NO FUEL TRANSFER NOTED.