What was found
GUM - FLT 275 - L/P 7016123 - DUE TO NR 1 FUEL MANIFOLD VALVE PREVIOUSLY PLACARDED (MEL 28-07, L/P 791622) AND THE MANIFOLD VALVE SAFETIED IN THE OPEN POSITION, FLIGHT CREW REPORTED NR 1 TANK BURNED FUEL REGARDLESS IF THE BOOST PUMPS WERE TURNED OFF WHEN ATTEMPTING TO BURN FUEL FROM NR 2 TANK. CREW AIR RETURNED TO GUAM. MAINTENANCE REMOVED AND RPELACED NR 1 FUEL MANIFOLD VALVE PER MM 28-22-01 AND OPERATION CHECKED NORMAL. (X)