What was found
ON CLIMBOUT AND LEVEL OFF AT FLT360, THE RIGHT FUEL QUANTITY INDICATOR STARTED SHOWING A RAPID DECREASE IN FUEL. IT SHOWED A LOSS @ 20# PER SECOND. IT STOPPED DECREASING @ 8.17#. THE LEFT QUANTITY IND SHOWED 8.61. AFTER IT STOPPED DECREASING AND THEN SLOWLY INCREASED TO 8.37 SLOWLY, TAKING TWO HOURS TO GET THERE. GROUNDED - YES. PERFORMED OPERATIONAL TEST OF THE FUEL QUANTITY INDICATING SYSTEM PER B737-800 AMM 28-41-00-710-801 AND FOUND NO FAULT. BOTH FLIGHT DECK INDICATOR AND UNDERWING FUEL QUANTITY INDICATOR SHOWED CORRECT FUEL AMOUNT.