What was found
AT TOP OF CLIMB CENTER FUEL TANKS EMPTY WITH FUEL BALANCED. T/C +60 MIN SHOWED AND INCREASING IMBALANCE WITH MAIN FUEL TANK #1 DIVERGING LOWER/FASTER THAN MAIN TANK #2FUEL USED INDICATION WAS WITHIN 70#, BUT TANK #1 WAS 860# LOWER BEFORE WE FOLLOWED QRH AND BALANCED FUEL APPROX 30 MIN BEFORE TOP OF DESCENT. #1 FUEL TANK CONTINUED TO DRAIN FASTER AT APPROX 400# PER HOUR FASTER THAN TANK #2. TOTAL TRIP FUEL USED WAS 1200# MORE THAN FLIGHT PLAN. GROUNDED - YES. FUEL QTY SYS TESTS GOOD. ACCOMPLISHED #1 FQIS TANK AND COMPENSATOR RESITANCE AND CAPACITANCE CHECK REF MM 28-41-21. ALL VALUES WITHIN LIMITS. PERFORMED CROSSFEED VALVE FUNCTIONAL TEST, TEST FAILED. FUEL TRANSFERRED 3 PANELS IN 3 MIN FROM 1 TO TANK 2. PERFORMED CROSSFEED VALVE ALINGMENT, OPS CHECK AND FUNCTIONAL TEST OF CROSSFEED VALVE REF AMM 28-22-00 AND 28-22-21.