What was found
HAD THE ODOR OF FUEL IN THE COCKPIT DURING PREFLIGHT WITH AP & PACKS RUNNING. THE ODOR WENT AWAY, AND TOOK OFF. PASSING ABOUT FL 230, THE ODOR CAME BACK WITH NO ASSOCIATED INDICATIONS, IT WENT AWAY. THEN PASSING FL 270 THE ODOR CAME BACK BUT STRONGER. CREW WENT ON O2 MASKS & RAN THE CHECKLIST & ODOR WAS CHECKED ABOUT 10,000 ON DESCENT & ODOR WAS GONE AGAIN. DIVERTED BACK, NO INCREASE OF OIL QTY WAS OBSERVED. R & R PACKS 1, 2 & 3 COALESCER BAGS IAW MM 21-54-03-2. RAN ALL 3 ENGINES AT PART POWER, WITH 1 PACK AT A TIME & THEN ALL 3 PACKS FOR APPROX 25 MIN, NO ODORS NOTED AT THIS TIME IAW MM 21-53-00-7.