What was found
(CAN) CONTAMINANTS ARE MIGRATING INTO THE RELIEF VALVE SEAT AND WALLS CAUSING GALLING WITHIN THE RELIEF VALVE. THIS CAUSES THE VALVE TO STICK CAUSING PRESSURE IMPULSES FROM THE ENGINE DRIVEN PUMP NOT TO BE ABSORBED BY THE RELIEF VALVE. THE IMPULSE CAUSE THE VACUUM SWITCH IN THE GASCOLATOR TO FLICKER THE WARNING LIGHT. FURTHER INVESTIGATION DURING THE TEARDOWN REVEALED CONTAMINATES WITHIN THE HSG. WHEN THE PRESSURE RELIEF VALVE IS STUCK PROPER FUEL PRESSURE WILL NOT BE MAINTAINED CAUSING ADVERSE ENGINE OPERATING CONDITIONS.