0342763 JOHNSON SPRING, Diaphragm return

Recommended Actions
Diagnostic Codes, Event Codes, and Electrical Power Supply to the ECM
Certain diagnostic codes and/or event codes may prevent the engine from starting. Connect Caterpillar Electronic Technician (ET) and check for active codes and/or for logged codes. Troubleshoot any codes that are present before continuing with this procedure.Note: If Cat ET will not communicate with the ECM, the problem is most likely with the electrical power supply to the ECM. Refer to Troubleshooting, "Electrical Power Supply - Test".Flash File
Verify that the latest flash file has been installed into the ECM.Throttle Signal
Monitor the status for "Throttle Position" on Cat ET. Verify that the status for "Throttle Position" is stable and that the engine is able to reach high idle speed. Refer to Troubleshooting, "Speed Control - Test".Injection Actuation Pressure
Check the engine oil level. Engine oil supplies the injection actuation pressure circuit. The engine oil must be kept at the proper level for fuel injection.
If service has recently been performed on the engine, air may be present in the injection actuation pressure circuit. Allow the engine to fully warm up and operate the engine under load in order to purge the air from the injection actuation pressure circuit.
Perform the "Injection Actuation Pressure Test " in Cat ET. Check the injection actuation pressure. If necessary, check the operation of the injection actuation pressure control valve. Refer to Troubleshooting, "Injection Actuation Pressure Control Valve - Test".Electrical Connectors
Disconnect the J1/P1 and J2/P2 ECM connectors. Inspect each connector for moisture and corrosion. Also, inspect the harness and connectors for the unit injectors from the ECM to the valve cover. Inspect the connectors for the engine speed/timing circuit. Refer to Troubleshooting, "Electrical Connectors - Inspect".Circuit Breakers
Check for circuit breakers that are tripped. If a circuit breaker is tripped, reset the circuit breaker. Determine the cause of a tripped circuit breaker."Turbocharger Outlet (Boost) Pressure Sensor"
Monitor the status of "Fuel Position", "Rated Fuel Limit", and "FRC Fuel Limit" on Cat ET while the engine is operating under full load. These parameters should agree with 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 correctly. Otherwise, proceed with the next step.
Monitor the status of "Turbocharger Outlet (Boost) Pressure" and "Atmospheric Pressure" for normal operation on Cat ET. When the engine is not running, "Turbocharger Outlet (Boost) Pressure" should be 0 kPa (0 psi).Air Inlet and Exhaust System
Check the air filter restriction indicator for a plugged filter. If necessary, service the engine. Refer to the Operation and Maintenance Manual.
Check the air inlet and exhaust system for restrictions and/or leaks. Refer to Systems Operation/Testing and Adjusting.Fuel Supply
Visually check the fuel level. Do not rely on the fuel gauge only. If necessary, add fuel. If the engine has been run out of fuel, it will be necessary to prime the fuel system. Refer to Operation and Maintenance Manual for the correct procedure.
Check the fuel lines for the following problems: restrictions, collapsed lines and pinched lines. If problems are found with the fuel lines, repair the lines and/or replace the lines.
Check the fuel tank for foreign objects which may block the fuel supply.
Do not crank the engine continuously for more than 30 seconds. Allow the starting motor to cool for two minutes before cranking the engine again.
Prime the fuel supply system if any of the following procedures have been performed:
Replacement of the fuel filters
Service on the low pressure fuel supply circuit
Replacement of unit injectorsNote: A sight glass in the supply line is helpful in diagnosing air in the fuel. Refer to the Systems Operation/Testing and Adjusting manual for more information.
Cold weather adversely affects the characteristics of the fuel. Refer to the Operation and Maintenance Manual for information on improving the characteristics of the fuel during cold weather operation.
Check fuel flow after the fuel filters. If the fuel flow is low, replace the fuel filters. If the fuel flow is still low, check the following items: fuel transfer pump, fuel transfer pump coupling and fuel pressure regulating valve.Starting Aids (if applicable)
If cold ambient conditions exist, check operation of starting aids. Refer to the appropriate starting aid test(s).
Ensure the proper operation of the jacket water heater. Repair the jacket water heater and/or replace the jacket water heater, if necessary.
Check for presence of solidified fuel (wax).Engine Shutdown Switches (if applicable)
The engine shutdown switches should be in the OFF position. Use Cat ET to verify the status of the shutdown switches. When a shutdown occurs, the keyswitch must be turned to the OFF position for at least 15 seconds before restarting the engine.Engine Speed/Timing
Crank the engine and observe the engine speed on the Cat ET status screen. If Cat ET indicates zero rpm, refer to Troubleshooting, "Speed/Timing - Test".Note: Upon initial cranking, the status for engine speed may indicate that the engine speed signal is abnormal. This message will be replaced with an engine speed once the ECM is able to calculate a speed from the signal.
Ensure that the timing reference gear is installed correctly. The engine will not start if the gear was installed backward. Check for proper orientation between the crankshaft and camshaft drive gears. Correct the orientation and/or replace the drive gear, if necessary. Refer to the Disassembly and Assembly manual.Unit Injectors
Perform the "Injector Solenoid Test" on Cat ET in order to determine if all of the injector solenoids are being energized by the ECM. Refer to Troubleshooting, "Injector Solenoid - Test" for additional information.Combustion
Check for mechanical problems in the combustion system.