What was found
RAN XFEED & FUEL TRANSFER NORMAL. WHEN CLOSING XFEED BOTH BOOST PUMP LIGHTS ILLUMINATED & STAYED ILLUM STEADY, NO FLASHING & NO MASTER CAUTION. UNABLE TO TRANSFER FUEL WITH BOOST PUMPS RUNNING. POWERED ON BATTERY & OPS FUEL BOOST PUMPS, NO DEFECTS, STARTED APU & OPS FUEL XFEED SYS, NO DEFECTS, SYS ACTIVATES & DE-ACTIVATES GOOD, STARTED ENGS & RAN XFEED SYS AGAIN, ALL NORMAL, LT XFEED IN LT TO RT & RT TO LT FOR 10 MINS, ALL NORMAL, SHUTDOWN ENGS & OPS SYS MULTIPLE TIMES, NO DEFECTS, POWERED DOWN ACFT, ADVISED THE RT MOTIVE FLOW SHUTOFF VALVE IS LIKELY SUSPECT CAUSE OF PROBLEM, POWERED UP ACFT, RAN XFEED SYS, NO DEFECTS, R & R RT MOTIVE FLOW SHUTOFF VALVE WITH NEW IAW MM 28-21-06, OPS & LEAK CHK GOOD.