What was found
FUEL CONFIG CAS IN CRZ. IMBALNCE OF 1900LBS. FM SUGGESTED POSS FUEL LEAK RTRNED TO LHR. CREW DEBRIEF C/OUT ON A/C RTN - REF MADE TO LP 3937863 - LEFT CTR FUEL PUMP INOP AS PER MEL 2822G. NIL FUEL LEAKS FOUND ON ARRIVAL. CREW BALANCED FUEL INBOUND, LEFT & RIGHT WING TANK BOTH INDICATE 35.8 / CTR TANK INDICATES 0.0. BOTH FLT DECK AND WING GAUGES INDICATE SAME TOTALS. DURING DEBRIEF DISCUSSED FLT CREW INSTRUCTION AND SW POSITION FOR DEPARTURE WITH ALL CREW. SUSPECT A/C DEPARTED WITH NO CROSSFEED VALVE SELECTED TO ON POSITION AS PER FLIGHT CREW INSTRUCTION IN MEL. TOMC INFORMED.