0391508 JOHNSON FLOAT ASSY.

Probable Causes
Diagnostic codes and event codes
Air inlet or exhaust system
Atmospheric pressure sensor
Intake manifold pressure sensor
Fuel quality
Low-pressure fuel system
Valve lash adjustment
Gear train problem
Flash fileRecommended Actions
Table 1
Troubleshooting Test Steps Values Results
1. Check for Codes
A. Connect Caterpillar Electronic Technician (ET) to the service tool connector. Refer to Troubleshooting, "Electronic Service Tools", if necessary.
B. Download the "Product Status Report" from the engine ECM before performing any troubleshooting or clearing diagnostic trouble codes.
C. Determine if the diagnostic trouble code that directed to this procedure is present.
D. Look for active diagnostic codes that are associated with the system for the event code that directed to this procedure.
Codes
Result: An associated code is present.
Repair: Troubleshoot any associated codes before continuing with this test.
Result: A code is present for an exhaust port temperature.
Proceed to the next step.
Result: No active codes
STOP
2. Check the Air Inlet or Exhaust System
A. Check the air inlet system for restrictions and/or for leaks.
1. Check for an air filter restriction.
2. Perform a visual inspection of the system for damage or restrictions. Also, inspect the air inlet system for air leaks in the piping.
B. Ensure that the turbochargers are in good repair.
C. Check the exhaust system for restrictions.
Leaks, Restrictions, or Damage
Result: The air inlet and exhaust system are OK.
Proceed to the next step.
Result: The air inlet and/or exhaust system are NOT OK.
Repair: Any leaks that were found. Remove any restrictions that were found. Replace any damaged components that were found.
If the problem is not resolved, proceed to the next step.
3. Inspect the Atmospheric Pressure Sensor
A. Check the atmospheric pressure sensor for dirt and/or for debris.
50 kPa (7 psi) - 100 kPa (14psi)
Result: The atmospheric pressure sensor is 50 kPa (7 psi) - 100 kPa (14psi).
Proceed to the next step.
Result: The atmospheric pressure sensor is not 50 kPa (7 psi) - 100 kPa (14psi).
Repair: Remove any dirt and/or debris that is present.
If the problem is not resolved, proceed to the next step.
4. Monitor the Intake Manifold Pressure Sensor, "Fuel Position", and/or "FRC Fuel Limit"
1. Monitor the status of "Fuel Position" and "Rated Fuel Limit" while the engine is operating under full load.
2. Verify that there are no active diagnostic codes for the intake manifold pressure sensor.
3. Monitor the status of "Intake Manifold Pressure" and "Intake Manifold #2 Pressure" on Cat ET without engine running.
Sensor
Result: If "Fuel Position" equals "Rated Fuel Limit" and "Fuel Position" is less than "FRC Fuel Limit", the ECM is providing the correct control.
Continue with this step.
Result: "Intake Manifold Pressure" and "Intake Manifold #2 Pressure" should be approximately 0 kPa (0 psi).
Proceed to the next step.
Result: "Intake Manifold Pressure" and "Intake Manifold #2 Pressure" is not approximately 0 kPa (0 psi).
Repair: Replace intake manifold sensor.
If the problem is not resolved, proceed to the next step.
5. Check the Fuel Quality
A. Check the fuel analysis.
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.
Fuel
Result: The fuel quality is OK.
Proceed to the next step.
Result: The fuel quality is NOT OK.
Repair: For further information, refer to the engine Operation and Maintenance Manual.
If the problem is not resolved, proceed to the next step.
6. Check the Low Pressure Fuel System
A. Perform a visual inspection of the fuel system components.
B. Check the fuel pressure during engine cranking. Refer to Systems Operation/Testing and Adjusting for the correct pressure values.
C. Check the filtered fuel pressure. Refer to Systems Operation/Testing and Adjusting for the correct pressure values.
D. Check for air in the fuel system. Refer to Systems Operation/Testing and Adjusting for details.
Fuel Pressure
Result: The fuel pressure is OK.
Continue with this step.
Result: The fuel pressure is low.
Repair: Replace the fuel filters. If the fuel pressure is still low, refer to Troubleshooting, "Fuel Pressure is Low" for more information that is related to troubleshooting the low-pressure fuel system.
If the problem is not resolved, proceed to the next step.
7. Check the Valve Lash Adjustment
A. Check valve lash.
Valve Lash
Result: The valve lash is OK.
Proceed to the next step.
Result: The valve lash is NOT OK.
Repair: Refer to Systems Operation/Testing and Adjusting for information related to valve adjustments.
If the problem is not resolved, proceed to the next step.
8. Check for a Gear Train Problem
A. Inspect the crankshaft and camshaft gears for proper orientation.
B. Check gear train for excessive wear.
Timing and Wear
Result: The crankshaft and camshaft gears are in time.
Continue with this step.
Result: The crankshaft and camshaft gears are not in time.
Repair: Refer to the Disassembly and Assembly manual for engine timing.
Result: Gear train has excessive wear.
Repair: Refer to the Reuse and Salvage Guidelines manual.
Result: Gear train does not have excessive wear.
If the problem is not resolved, proceed to the next step.
9. Check the Flash File
A. Check for correct flash file.
Flash File
Result: The flash file is OK.
Result: The flash file is NOT OK.
Repair: Verify that the latest flash file is installed. Refer to Troubleshooting, "ECM Software - Install" for information.