14479 Mercury DIAPHRAGM

Table 1
Event Code    
Description    Default Conditions which Generate this Code    System Response    
E198(1) Low Fuel Pressure     The fuel pressure drops below
175 kPa (25 psi) for ten seconds.     The code is logged.    
E198(2) Low Fuel Pressure     The fuel pressure drops below
150 kPa (22 psi) for 15 seconds.     The code is logged.
The engine is derated.    Probable Causes
Fuel level
Fuel tank cap
Diagnostic codes and event codes
Fuel pressure sensors
Fuel pressure regulating valve
Fuel priming pump
Fuel transfer pumpRecommended Actions
Fuel Level
Visually inspect the fuel level in the fuel tank. Ensure that the fuel tank contains enough fuel in order to operate the engine.Fuel Tank Cap
Remove the fuel tank cap from the fuel tank. Check the vent port that is in the cap for debris. Clear any restrictions with compressed air.Note: Do not allow debris to enter the fuel tank while you clean the cap. Damage to the fuel system will occur.Diagnostic Codes and Event Codes
Connect Caterpillar Electronic Technician (ET) to the service tool connector. Check for active diagnostic codes and event codes.Look for active diagnostic codes that are related to the low pressure fuel system. Use the appropriate circuit test to troubleshoot any active codes before continuing.Fuel Pressure Sensors
Start the engine. Run the engine at low idle. Use Cat ET to monitor the fuel pressure for the engine.Check the value of the parameter while the engine is at low idle. Ensure that the value of the parameter is reasonable.Increase the engine speed while you monitor the parameter. Ensure that the value of the parameter increase with engine speed. Ensure that the value of the sensor remains reasonable as the pressure is increased.If a problem with the sensor is suspected, replace the suspect sensor.Fuel Pressure Regulating Valve
A fuel pressure regulating valve that is stuck in the open position may cause low fuel pressure. If a problem with the valve is suspected, the problem is probably caused by contamination or debris lodged between the valve and the valve seat. Remove the valve assembly from the fuel filter base. Inspect the valve assembly for contamination or debris. Clean any contamination or debris that may keep the regulating valve open. If debris is present, find the source of the contamination.If the fuel pressure regulating valve is the suspected cause of the low fuel pressure, replace the valve assembly.Fuel Priming Pump
The electric fuel priming pump is used to prime the low pressure fuel system. Ensure that the electric fuel priming pump is achieving the correct pressure. Refer to Systems Operation/Testing and Adjusting for additional information that is related to testing the low pressure fuel system.Fuel Transfer Pump
The fuel transfer pump may not be pumping an adequate volume of fuel in order to maintain the correct pressure in the low pressure fuel system. If the correct pressure in the low pressure fuel system is not maintained during start-up the engine will start, but the engine will not continue running.Use Cat ET to monitor the "Fuel Pressure" status parameter during engine starting.If the other components in the fuel system are operating within specifications, and the fuel pressure decreases after starting the engine, replace the fuel transfer pump.