What was found
FUEL PRESSURE GAUGE USED ON MODEL C3 AND C3T BURNER ASSY HAS AN OPERATING RANGE OF ZERO TO 200 PSI. WHEN FUEL TANK PRESSURE IS ABOVE 150 PSI, OPENING THE LIQUID FUEL SHUT-OFF VALVE ON THE TANK CAUSES A PRESSURE SURGE IN THE BURNER FUEL SYSTEM DRIVING THE PRESSURE GAUGE BEYOND ITS OPERATING LIMIT DAMAGING ITS INTERNAL MECHANISM. THE GAUGE IS NOT REPAIRABLE AND MUST BE REPLACED WHEN DAMAGED. THIS HAS BEEN A RECURRING PROBLEM IN 10 BURNER SYSTEMS.