B767 BEING FUELED PRIOR TO FLT AND FUEL XFERRED OUT OF THE CTR TANK WITH THE XFEED VALVE OPEN. FUELER FAILED TO CLOSE THE XFEED AND FLC DIDN'T NOTICE IT UNTIL INFLT WHEN A 5000 LB IMBALANCE BECAME EVIDENT.

Narrative

AFTER DOING ORIGINAL PREFLT; A FUELER CAME UP TO CHANGE THE FUEL PANEL TO XFER SOME FUEL OUT OF THE CTR TANK TO GET THE LEVEL DOWN TO 1000 LBS TO COMPLY WITH THE NEW FAA DIRECTIVE. WE DEPARTED NORMALLY; WITH THE FUEL CONFIGN LIGHT ON DUE TO THE FUEL IN THE CTR TANK WITH THE PUMPS OFF. ON ENRTE FUEL CHKS; I NOTED TOTAL FUEL AND THAT THE FUEL CONFIGN LIGHT WAS STILL ON. LATE IN THE FLT; I NOTED A LARGE IMBALANCE BTWN THE WING TANKS. IT WAS THEN THAT WE DISCOVERED THE XFEED VALVE HAD NEVER BEEN CLOSED BY THE FUELER IN LAX. DUE TO OUR BELIEVING THE FUEL CONFIGN LIGHT WAS BECAUSE OF THE CTR TANK LIMITATION; WE NEVER SUSPECTED ANYTHING ELSE. WE THEN TURNED OFF THE R WING FUEL PUMPS; LEAVING THE XFEED OPEN. ON LNDG AT MIA; WE HAD ABOUT A 5000 LB IMBALANCE IN THE WING TANKS. LNDG WAS NORMAL AND MAINT WAS NOTIFIED; THOUGH THEY DIDN'T FEEL ANY ACTION WAS NECESSARY. SUPPLEMENTAL INFO FROM ACN 384570: FUELER AT LAX OPENED XFEED TO REDUCE FUEL IN CTR TANK. I MISSED CLOSING THE XFEED. HAD 2 MEDICAL EMERS. CHKED TOTAL FUEL AT EACH WAYPOINT BUT MISSED XFEED AND FUEL IMBALANCE. CAUGHT DIFFERENCE TO LAND WITH APPROX 5000 LB FUEL IMBALANCE. MY MISTAKE BUT THIS IS A FALLACY OF HAVING CTR TANK FUEL WITH PUMPS OFF AND FUEL CONFIGN LIGHT ON.