0396397 JOHNSON FUEL TANK & HOSE ASSEMBLY

Probable Causes
Diagnostic codes
Air Intake and Exhaust System
Fuel System Inspection
Throttle Position Sensor/Throttle Switches
High-pressure fuel pump
Low compression (cylinder pressure)
Electronic unit injectors
Individual malfunctioning cylinderRecommended Actions
Note: The procedures have been listed in order of probability. Complete the procedures in order.
Table 1
Troubleshooting Test Steps Values Results
1. Diagnostic Codes
A. Establish communication between the electronic service tool and the Electronic Control Module (ECM). Refer to Troubleshooting, "Electronic Service Tools", if necessary.
Diagnostic codes
Result: There are active codes.
Repair: Troubleshoot any active codes before continuing with this procedure.
Result: There are no active codes.
Proceed to Test Step 2.
2. Air Intake and Exhaust System
A. Check the air filter restriction indicator.
B. Ensure that the air filter is clean and serviceable
C. Check the air intake and exhaust systems for the following defects:
Blockages
Restrictions
Damage to lines or hoses
Fuel System
Result: A defect was found in the air intake or exhaust system.
Repair: Make any necessary repairs.
Result: No defects found in the air intake or exhaust systems.
Proceed to Test Step 3.
3. Fuel System Inspection
A. Check that the fuel shut-off valve is in the OPEN position.
B. If the temperature is below 0 °C (32 °F), check for solidified fuel (wax).
C. Check for fuel supply lines that are restricted.
D. Check that the low-pressure fuel lines are correctly installed.
E. Check the pressures in the fuel system. Refer to Systems Operation, Testing, and Adjusting, "Fuel System Pressure - Test"
F. Check the diesel fuel for contamination. Refer to Systems Operation, Testing, and Adjusting, "Fuel Quality - Test".
G. Check for air in the fuel system. Refer to Systems Operation, Testing, and Adjusting, "Air in Fuel - Test".
H. Ensure that the fuel system has been primed. Refer to Systems Operation, Testing, and Adjusting, "Fuel System - Prime".
Fuel supply
Result: A defect was found in the fuel system.
Repair: Make any necessary repairs.
Result: No defects found.
Proceed to Test Step 4.
4. Throttle Position Sensor/Throttle Switches (if equipped)
A. Turn the start switch to the ON position.
B. Run the engine until the speed is equal to the maximum no-load speed.
C. Use the electronic service tool to make sure that the throttle is set to reach the maximum no-load speed.
Electrical connections
Result: The throttle response is not as expected.
Repair: If the maximum no-load speed cannot be obtained refer to Troubleshooting, "Switch Circuits - Test (Throttle Switch)" and Troubleshooting, "Mode Selection - Test".
If the engine speed is erratic refer to Troubleshooting, "Speed Control - Test".
Result: All responses are normal.
Proceed to Test Step 5.
5. High-Pressure Fuel Pump
Note: The fuel injection pump that is installed by the factory is a nonserviceable item. If any fault occurs within the fuel injection pump, the fuel injection pump must be replaced.
A. Use the electronic service tool to select the correct screen in order to display any diagnostic trouble codes that relate to the fuel injection pump.
HP fuel pump
Result: There are diagnostic codes associated with the high-pressure fuel pump.
Repair: Diagnose the codes. Refer to Troubleshooting, "Diagnostic Trouble Codes".
If necessary, replace the high-pressure fuel pump.
Result: The high-pressure fuel pump is OK.
Proceed to Test Step 6.
6. Low Compression (Cylinder Pressure)
A. Perform a compression test. Refer to Systems Operation, Testing, and Adjusting, "Compression - Test ".
Cylinder compression
Result: The results of the compression test are outside the specifications.
Repair: Investigate the cause and rectify any faults.
Note: Possible causes of low compression are shown in the following list:
Loose glow plugs
Faulty piston
Faulty piston rings
Worn cylinder bores
Worn valves
Faulty cylinder head gasket
Damaged cylinder head
Result: The results of the compression test are OK.
Proceed to Test Step 7.
7. Electronic Unit Injectors
A. Use the electronic service tool to check for active diagnostic codes that relate to the electronic unit injectors.
Diagnostic codes
Result: There are active diagnostic codes relating to the fuel injectors.
Repair: Troubleshoot any active diagnostic codes associated with the fuel injectors. Refer to Troubleshooting, "Diagnostic Trouble Codes"
Result: All injectors are OK.
Proceed to Test Step 8.
8. Individual Malfunctioning Cylinders
A. With the engine speed at a fast idle, use the electronic service tool to perform the manual "Cylinder Cut Out Test". As each cylinder is cut out, listen for a change in the sound from the engine. When a cylinder is cut out, there should be a noticeable change in the sound of the engine.
Cylinders
Result: There is not a noticeable change in the sound of the engine for at least one cylinder.
Repair: Investigate the cause of the fault on any cylinder that is not operating. Investigate the cause of the fault on any cylinder that is operating below normal performance.
Result: There is a noticeable change in the sound of the engine for each cylinder.
Contact the Dealer Solution Network (DSN).