- The gas supply to the engine is insufficient.
- A feature for engine protection prevents the engine from starting.
- The starting motor circuit is faulty.
- There is no engine speed signal to the master Electronic Control Module (ECM).
- The ignition system is not functioning.
- The base timing is incorrect.
- The quality of the gas does not match the parameter for "Fuel Quality".
Check the Gas Supply to the Engine
Check for low gas pressure. If the gas pressure is low, refer to Troubleshooting, "Fuel Pressure".
If the throttle does not open, check for binding of the throttle actuator. Move the throttle plate while you feel the motion. If the motion is sticky and/or rough, investigate the cause of the binding. Make the necessary repairs.
Check for binding of the fuel metering valve. Move the plate while you feel the motion. If the motion is sticky and/or rough, investigate the cause of the binding. Make the necessary repairs.
Use the Caterpillar Electronic Technician (ET) to check for active diagnostic codes or for event codes which may prevent the engine from starting.
Correct the cause of the active code. Before the engine can be started, you must cycle the power to the engine. Set the engine control to the OFF/RESET mode. Then set the control to the STOP mode.
Check the Status of the Relay for the Starting Motor
Attempt to start the engine while you observe the status of the relay for the starting motor on Cat ET.
If the status of the relay for the starting motor indicates that the engine should crank but no cranking occurs, troubleshoot the starting circuit. Refer to Troubleshooting, "ECM Output Circuit (Starting Motor)".
If cranking occurs, check the engine rpm.
The master ECM must detect a minimum of 50 rpm before the gas and the ignition are supplied to the engine. Use Cat ET to monitor the engine speed while you crank the engine.
If no engine speed is displayed on Cat ET or if the engine speed is not stable, troubleshoot the speed/timing sensor. Refer to Troubleshooting, "Engine Speed/Timing Sensor".
Check for active diagnostic codes that relate to the ignition system. If there is at least one active diagnostic code that relates to the ignition system, troubleshoot the diagnostic code.
Verify that the base timing is correct. Refer to Systems Operation/Testing and Adjusting, "Ignition Timing - Adjust".
Compare the Low Heat Value (LHV) of the gas supply to the "Fuel Quality" parameter that is programmed by the customer into the master ECM. The master ECM uses the setting for start-up and for air/fuel ratio control at low loads.
If the LHV of the fuel does not match the "Fuel Quality" parameter that is programmed into the master ECM, program the master ECM with the correct setting for the "Fuel Quality" parameter.