What was found
IN CRUISE FLT, AT FL 330, AT APPROX TAKEOFF PLUS FOUR HOURS, RECEIVED (LEVEL 1 TANK 2 FUEL QTY LO) ALERT S.D. FUEL READINGS WERE: 1- 900 2- 0 3-900 AUX- 900 TAIL- 12900. FUEL INDICATIONS AND USAGE TO THAT POINT HAD BEEN NORMAL. FSC WAS IN AUTO, ALSO GOT LEVEL 1 ALERT (FUELMANF DRAIN) AND DRAIN WAS ILLUMINATED OVERHEAD IN THE GUARDED MANF SWITCH. GOT A LEVEL 2 FUEL QTY/USED CHECK ALERT AS WELL AS LEVEL 2 FUEL QTY FAULT ALERT CHECKLIST FOR FUEL MANF DRAIN DIRECTS CREW NOT TO PRESSURIZE CROSSFEED MANIFOLD AS A RESULT WE KEPT FSC IN AUTO AND DIVERTED TO KMSP. REMOVED AND REPLACED S.E.M AND FUEL QUAN. DATA CONTROL UNIT IAW M/M. SYS OP'S CHECKS NORMAL AT THIS TIME. OK TO CONTINUE.