What was found
FUEL CONFIG MSG. C/W QRH PROCEDURE. FUEL LEAK NOT SUSPECTED. L QTY 6.6 R QTY 8.4 TOT 15.0 FUEL USED L13.4 FUEL USED R 14.0 TOTALIZER 15.0 CALCULATED 14.8 FF L3.4 FF R3.6 INBALANCE INCREASE 800 LB HR PER MX CONTROL TELEMETRY SHOWED AN IMBALANCE OF BELOW 1000LBS PER HOUR. PERFORMED FIM 28-21-00 AND DETERMINED ONE OF THE CROSSFEED VALVES IS MOST LIKELY INTERNALLY LEAKING. RECOMMEND CHANGING BOTH VALVES DURING TANK DIVE. ITEM IS DEFERRED PER AMM REF. 28-21-00-702-001 PARA B(2) FOR 4 FLIGHT CYCLES DUE TO HISTORY OF SLOW FUEL MIGRATION.