What was found
(CAN)DURING CRUISE THE LEFT FUEL TANK BOOST PUMPS LOW PRESSURE WARNING ANNUNCIATED (BOTH PUMPS). OPENED FUEL CROSSFEED, UNABLE TO MAINTAIN FUEL BALANCE IN THIS CONFIGURATION WITH #1 AND #2 FUEL PUMPS (TANK1) STILL SELECTED ON. DIVERTED AIRCRAFT TO YXE. MAINTENANCE ACTION INVOLVED HANGARING AIRCRAFT, DRAINED FUEL SUMPS, FOUND ICE CRYSTALS IN THE FUEL. AIRCRAFT REFUELED AND RETURNED TO SERVICE.