What was found
DURING OPERATIONS FOR WEIGHT & BAL PURPOSES, FUEL VALVE TURNED TO 'OFF'. AS VALVE WAS BEING TURNED BACK TO 'ON', IT BECAME STUCK IN INTERMEDIATE POS. LINKAGE BTWN COCKPIT & VALVE CHKD & FND IN PROPER ORDER. AFTER 2 OR 3 ATTEMPTS, VALVE RETND TO 'ON'. WHILE PERFORMING A COLD FUEL TEST, VALVE AGAIN BECAME STUCK & COULD NOT BE RETND TO OPEN. AFTER SEVERAL ATTEMPTS, VALVE WAS RETND TO OPEN. FUEL BOOST PUMP TURNED ON BUT COULD NOT GET FUEL TO ENG LINE. VALVE REMVD & COVER PLATE REMVD FROM VALVE. CAM THAT POSITIONS INTERNAL PLUNGERS BROKEN & JAMMED IN OUTLET PORT. PLUNGERS BEING SPRING LOADED TO CLOSED POS WERE PREVENTING FUEL TO FLOW TO ENG. HAD MALFUNCTION OCCURRED DURING FLIGHT, ENG WOULD HAVE QUIT.