As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
LEFT WING FUEL IMBALANCE WHEN CENTER FUEL USED. IMBALANCE SEEMED TO TERMINATE WHEN CENTER FUEL AT 11,000 LBS. OPERATES NORMAL WITH CENTER FUEL AT 0 AND BALANCED. NO FUEL LEAK PERCIEVED. AIRCRAFT WAS GROUNDED. MAINTENANCE REPLACED THE AFT CROSSFEED VALVE, FORWARD CROSSFEED VALVE AND THE LEFT FUEL PUMP VAPOR RETURN LINE.