As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FLT 1216 BUF-BOS AIR RETURNED TO BUF, ON TAKEOFF GOT DEFUEL SOV OPEN CAS MSG AND FUEL FEED FAULT MSG. FOLLOWED BY FUEL IMBALANCE AND FUEL LOW WARNING. TANK WAS DROPPING RAPIDLY WHILE TANK 2 WAS INCREASING. ON RETURN TO GATE, NR 1 SHOWED 4000 LB WHILE NR 2 HAD INCREASED TO 9000 LB. REMOVED AND REPLACED DEFUEL VALVE ACTUATOR PER AMM 28-83-07. OPS CHECK GOOD.