What was found
LEFT WING STARTED VENTING FUEL IN CLIMBOUT. AFTER TROUBLESHOOTING TECHNICIANS FOUND LEFT WING OUTBOARD AFT VENT FLOAT/ NON RELIEVING VALVE TO BE INOP. REPLACED VALVE WITH A NEW VALVE, P/N 16F123 AND SEAL, P/N GA215-160 IAW GULFSTREAM G-IV MAINTENANCE MANUAL 28-02-00 AND IPC 28-10-00. PERFORMED AIRCRAFT FUELING PROCEDURES IAW GULFSTREAM G-IV MAINTENANCE MANUAL 28-04-00. PERFORMED LEAK CHECK ON REMOVED WING ACCESS PANELS 21-FT16 AND 21-FT-17 WITH NO DISCREPANCIES. AIRCRAFT WAS RETURNED TO SERVICE.