As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING CRUISE, UNWANTED TRANSFER OF FUEL FROM THE CENTER TANK TO THE NR 1 LEFT MAIN TANK. AIRCRAFT WAS GROUNDED. REMOVED AND REPLACED LEFT MAIN FUEL SCAVENGE FLOAT OPERATED SHUT OFF VALVE IAW AMM 28-22-16. OPERATIONAL AND LEAK CHECK GOOD.