What was found
FUEL IN THE LEFT TANK INCREASED FROM 8.65 TP 8.79 AND STOPPED WHILE ENGINES WERE FEEDING FROM THE CENTER TANK. WITH LEFT TANK AT MAX CAPACITY OUR FUEL QUANTITY DECREASED FASTER THAN BURN RATE INDICATING . WERE VENTING FUEL. ONCE THE CENTER TANK WAS EMPTY VENTING STOPPED. REMOVED AND REPLACED FUEL QUANTITY PROCESSOR UNIT IAW AMM 28-41-81. ACCOMPLISHED ALL TANKS FUEL SUMPPED. ACCOMPLISHED FUEL QUANTITY INDICATING SYSTEM TEST, NO FAULT NOTED IAW AQMM 28-41-00. NO WATER NOTED IN THE TANKS OK FOR SERVICE.