3794 Mercury JET, MAIN FUEL (.074)

Recommended Actions
Note: If the problem only occurs under certain conditions, test the engine under those conditions. Examples of certain conditions are high engine speed, full load and engine operating temperature. Troubleshooting the symptoms under other conditions can give misleading results.Selected Engine Rating Parameters
Verify that the complaint is not due to a normal operation such as a programmed parameter. Connect the Caterpillar Electronic Technician (ET) and verify the various parameters. If the following diagnostic code is active, ensure that all the various parameters are programmed.
CID 268-FMI 02 Verify that the injector codes are programmed.Starting Aids
Air Inlet Heater
Make sure that the air inlet heater is programmed to the On position. For additional information on the air inlet heater, refer to Troubleshooting, "Air Inlet Heater Circuit - Test".Active Engine Derate
If an active derate occurs, the warning lamp will flash. "Engine Derate" will appear in the first engine status box on any Cat ET status screen. Verify that the set points for "Derate" that are in the programmable monitoring system have been programmed to the values that are correct. An SPN-FMI code will appear for an active derate on the Cat ET status screen that will display SPN diagnostic codes.Cat Data Link
The signal from the throttle switch is carried on the Cat data link. If the data link is not working properly, the engine will not receive the command for the high speed setting when the throttle switch is put into the high speed position. Refer to Troubleshooting, "CAT Data Link Circuit - Test".Electrical Connections
Check the electrical connections to the Electronic Control Module (ECM). Check all associated wiring for damage, for abrasion, for corrosion or for incorrect attachment. Refer to Troubleshooting, "Electrical Connectors-Inspect" for additional information.Circuit for the Hydraulic Electronic Unit Injector
Inspect the J2/P2 ECM connector and the J300/P300 unit injector connector for proper connections. Refer to Troubleshooting, " Electrical Connectors - Inspect". Connect Cat ET and cut out each cylinder in order to isolate the misfiring cylinder or cylinders. If the results are inconclusive, shut off half of the cylinders and repeat the cylinder cutout test on the active cylinders that are remaining in order to locate those cylinders that are missing. Refer to Troubleshooting, "Injector Solenoid Circuit - Test".Hydraulic Electronic Unit Injector Connector
Check the unit injector connectors J300/P300 and associated wiring for damage, abrasion, corrosion or incorrect attachment. Refer to Troubleshooting, "Electrical Connectors-Inspect" for additional information.Low Injection Actuation Pressure
Check the engine oil level. Engine oil is used to activate the high pressure hydraulic pump.
Ensure that the engine oil meets the recommendations of the engine manufacturer. Refer to Operation and Maintenance Manual for further details.
Crank the engine and monitor the injection actuation pressure and the output of the Injection actuation pressure control valve. The high pressure oil system is operating properly if the pressure output is a minimum of 6 MPa (870 psi).
Connect Cat ET and check for the following diagnostic code.
CID 164-FMI 11 If this diagnostic code has been logged recently, refer to Troubleshooting, "Injection Actuation Pressure -Test".Fuel Supply
Check for a problem with the fuel supply and verify the fuel pressure. Verify that the fuel pressure sensor P209/J209 is installed. For further information, refer to Testing and Adjusting, "Fuel System".Turbocharger Outlet Pressure Sensor (Intake Manifold Air), Rated fuel Position and/or FRC Fuel Position
Monitor the "Fuel Position", the "Rated Fuel Limit", and the "FRC Fuel Limit" on the status screen of Cat ET while the engine is operating under full load. These parameters should reflect the information below.
Table 1
"Fuel Position"="Rated Fuel Limit"
"AND"
"Fuel Position"<"FRC Fuel Limit" If "Fuel Position" equals "Rated Fuel Limit" and "Fuel Position" is less than "FRC Fuel Limit", the electronics are operating properly. Otherwise, proceed with the next step.
Monitor the status of "Turbo Outlet Pressure", "Boost Pressure", and "Atmospheric Pressure" while the engine is operating under full load.
Monitor the status of"Turbo Outlet Pressure", "Boost Pressure", and "Atmospheric Pressure" while the engine is operating at low idle.
Place the engine control in the OFF mode. The engine should be off. Place the engine control in the ON mode.
Monitor the status of "Turbo Outlet Pressure", "Boost Pressure", and "Atmospheric Pressure" for normal operation on Cat ET. When the engine is not running, "Turbo Outlet Pressure" should be equal to "Atmospheric Pressure". When the engine is not running, "Boost Pressure" should be 0 kPa (0 psi). Air Inlet and Exhaust System
Check air inlet and exhaust systems for restrictions and leaks. Refer to Testing and Adjusting, "Air Inlet and Exhaust System". Look for an indication of the warning lamp or restriction indicators that are tripped if the filters are equipped with these devices. These indicators are associated with plugged filters. Replace the plugged air filters or clean the plugged air filters per the guidelines for operation and maintenance. Repair any leaks that are found in the system.