What was found
ON FLIGHT 2750 THE CREW REPORTED THAT AFTER THE ENGINE START/SHUT DOWN OF APU, FUEL ODOR WAS DETECTED IN THE COCKPIT. THE ODOR THEN DISAPATED. EN ROUTE A HINT OF FUEL ODOR RETURNED. THE FLIGHT ATTENDANT REPORTED NO ODOR IN CABIN. THE AIRCRAFT WAS REMOVED FROM SERVICE. INSPECTED AND FOUND FUEL ODOR COMING FROM FUEL TRACKED INTO COCKPIT. CLEANED THE COCKPIT FLOOR. RAN PACKS, APU AND ENGINES. FOUND FUEL LEAKING FROM SINGLE POINT REFUELING RECEPTICAL. REMOVED AND REPLACED SINGLE POINT REFUELING ADAPTER VALVE IAW CMM 28-20-26. NO LEAKS NOTED. THE OPERATIONAL CHECK WAS GOOD. THE AIRCRAFT WAS RETURNED TO SERVICE.