What was found
AIRCRAFT WAS GROUNDED: PILOT REPORTS DURING CLIMB OUT FROM SNU, THE #1 N1 WAS 34% BELOW ON THE LEFT ENGINE FROM THE RIGHT ENGINE. EGT WAS 25 LESS, FUEL FLOW 0.50 LESS, BOTH BLEEDS & PACKS ON, ISOLATION VALVE-AUTO. INCREASING THRUST LEVER HAD NO EFFECT. ONCE IN CRUISE & DESCENT ALL ENGINE INDICATIONS WERE MATCHED UP. AUTO THROTTLE WAS ON THROUGHOUT EXCEPT WHEN MOVING THROTTLE. MAINTENANCE TROUBLESHOT TO ENGINE FUEL PUMP. MAINTENANCE REMOVED AND REPLACED FUEL PUMP IAW AMM 73-11-01. HMU REPLACED AS PRECAUTIONARY. ACCOMLISHED HIGH PWR RUN AND LEAK CHECK OK. OK FOR SERVCE.