5005924 JOHNSON Special Tools Catalog

Recommended Actions
Note: If the symptom only occurs under certain operating conditions (high idle, engine operating temperature, and so on.), test the engine under the conditions. Troubleshooting the symptom under other conditions can give misleading results.Incorrect Air/Fuel Ratio
An air/fuel mixture that is too lean will have an adverse effect on engine operation. Verify that the exhaust emissions are correct. Confirm that the sensor calibration for the NOX sensor is correct. Refer to Troubleshooting, "Nitrogen Oxide Sensor - Calibrate".A change in the fuel energy content will change the air/fuel ratio. Obtain a fuel analysis for the fuel supply.If the fuel analysis is as expected, inspect the NOX sensor port in the flower pot for plugging. If necessary, clean the port. If the problem persists, refer to Troubleshooting, "Detonation Occurrence".The fuel supply pressure must be 876 to 1289 mbar absolute or 12.705 to 18.695 PSI. The gas differential pressure (delta-p) should be between 69 and 345 mbar. Delta-p below this range is allowed during cranking and idle conditions, but accuracy of the valve will be reduced. For delta-p above 276 mbar, flow accuracy will also decrease, and a reduction in valve stability may occur. Minimum proof pressure for the fuel metering valve is 0.52 bar gauge. Minimum burst pressure for the fuel metering valve is 1.72 bar gauge.Incorrect Governor Adjustment
Governor gain settings that are negative values can result in slow engine response. The governor parameters must be programmed with the values that provide stable operation. Refer to Systems Operation/Testing and Adjusting, "Engine Governing - Adjust".Air Inlet Restriction
The maximum allowable air inlet restriction is 3.75 kPa (15 inches of H2O). If the indication is higher than the maximum permissible restriction, clean the filter element or install a new filter element. Check the restriction again. If the restriction remains too high, inspect the air inlet piping for obstructions.Fuel Metering Valve
Check the fuel metering valve for an internal mechanical failure:Shut off the fuel supply. Disconnect the fuel lines from the fuel metering valve. Visually inspect the internal mechanism of the valve. Check for binding due to dirt and/or to contamination. Check for binding due to wear of internal components.Clean the valve, if necessary.Compressor Bypass Valve
The compressor bypass valve and the compressor bypass actuator must be installed properly in order to provide stable operation. Inspect the mechanical condition of the components. Refer to the Disassembly and Assembly for information that is related to the correct installation of the compressor bypass valve and the compressor bypass actuator.Throttle Actuator
Set the engine control to the OFF/RESET position. Remove the electrical power from the engine. Move the throttle plate through the entire range of travel while you feel the motion. If the motion is sticky and/or rough, investigate the cause of the binding. Perform the necessary repairs.Exhaust Bypass Valve
An improperly adjusted exhaust bypass valve can affect engine performance. If the engine has experienced a change in the operating load, the operating altitude, or the ambient temperature check the setting of the exhaust bypass valve. Refer to Systems Operation/Testing and Adjusting, "Exhaust Bypass Valve - Adjust" for details.Aftercooler
A plugged aftercooler will adversely affect engine power. Check the aftercooler differential pressure. Refer to Systems Operation/Testing and Adjusting, "Restriction of Air Inlet and Exhaust". Clean the aftercooler, if necessary. Refer to the Operation and Maintenance Manual for details.Turbocharger
A worn turbocharger will adversely affect the power that is produced by the engine. Inspect the turbocharger housing for signs of damage. Ensure that the compressor wheel and turbine wheel have the proper clearance between the impeller blades and the housing.Fouling of the turbine wheel can contribute to a loss of engine power and a loss of engine efficiency. Check for debris buildup on the impellers of the turbine wheel and compressor wheel.Refer to Operation and Maintenance Manual, "Turbocharger-Inspect". Perform any necessary repairs.