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POSSIBLE CAUSES Are there any other DTC's present Fuel leaks Fuel control actuator Fuel pressure sensor Cascade overflow valve Check valve damaged or blocked Fuel return lines obstruction, damage, or debris. Lift pump flow Air in fuel system Leaking fuel injectors or high pressure connectors Pressure limiting valve High pressure fuel pump Intermittent condition
Diagnostic Test 1. OTHERS DTC'S PRESENT With the scan tool, read DTCs. Q: Are any other DTC's present? YES: Repair other DTC's first. Perform the POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). See: Verification Tests\Powertrain Verification Test - Ver 1 NO: Go To 2 2. FUEL LEAKS Ensure that the fuel level is above 15% using the scan tool. Visually inspect the low and high pressure side of the fuel system for fuel leaks or damaged components. Q: Do you have any fuel leaks or damaged components? YES: Repair the fuel leak. Perform the POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). See: Verification Tests\Powertrain Verification Test - Ver 1 NO: Go To 3 3. FUEL CONTROL ACTUATOR Check for a mechanically stuck Fuel Control Actuator (FCA). Using the scan tool, actuate the fuel control actuator. NOTE: The fuel control actuator will only click when cycled off. Q: Do you hear a click from the actuator when you cycle the actuator off with the scan tool? YES: Go To 4 NO: Replace the fuel Injector pump. Perform the POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). See: Verification Tests\Powertrain Verification Test - Ver 1 4. FUEL PRESSURE SENSOR Using the scan tool, monitor the fuel pressure reading from the fuel rail pressure sensor at idle and at 2000 RPM . Q: Is the fuel rail pressure reading higher at 2000 RPM than at idle? YES: Go To 5 NO: Replace the fuel pressure sensor. Perform the POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). See: Verification Tests\Powertrain Verification Test - Ver 1 5. HIGH FUEL PRESSURE Using the scan tool compare the fuel rail pressure set point with the actual fuel rail pressure. Q: Is the actual fuel rail pressure higher than the fuel rail pressure set point? YES: Go To 6 NO: Go To 9 6. CASCADE OVERFLOW VALVE Perform the no trouble code test 9*fuel pump return flow test 9. Q: Did the fuel injection pump pass the test? YES: Go To 7 NO: Replace the Fuel pump. Perform the POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). See: Verification Tests\Powertrain Verification Test - Ver 1 7. CHECK VALVE DAMAGED OR BLOCKED Check the fuel drain line check valve in the rear of the cylinder head for signs of damage, blockage, or debris. Q: Is the check valve damaged or blocked? YES: Repair the cause of the damaged or blocked check valve or replace the valve. Perform the POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). See: Verification Tests\Powertrain Verification Test - Ver 1 NO: Go To 8 8. FUEL RETURN LINE OBSTRUCTION, DAMAGED OR DEBRIS Check the fuel return lines for signs of obstruction, damage, or debris. Q: Are the fuel drain lines damaged or blocked? YES: Repair cause of high fuel drain line restriction. Perform the POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). See: Verification Tests\Powertrain Verification Test - Ver 1 NO: Go To 9 9. LIFT PUMP FLOW Perform the no trouble code 9Lift Pump flow test 9. Q: Did the Lift pump pass the test? YES: Go To 10 NO: Replace the Lift Pump. Perform the POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). See: Verification Tests\Powertrain Verification Test - Ver 1 10. PRESSURE LIMITING VALVE Perform the no trouble code test 9 Pressure Limiting Valve on the Fuel Rail for internal leaks9. Q: Did the pressure limiting valve pass the test procedure? YES: Go To 11 NO: Replace the Pressure Limiting Valve. Perform the POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). See: Verification Tests\Powertrain Verification Test - Ver 1 11. LEAKING FUEL INJECTORS OR HIGH PRESSURE CONNECTORS Perform the no trouble test 9*Injector return flow test 9. Q: Are any Injectors leaking or high pressure connectors leaking? YES: Replace or repair the leaking fuel injectors or high pressure connectors. Perform the POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). See: Verification Tests\Powertrain Verification Test - Ver 1 NO: Go To 12 12. HIGH PRESSURE FUEL PUMP Perform the no trouble code test 9HIGH PRESSURE FUEL PUMP PERFORMANCE TEST 9. Q: Did the fuel pump pass the high pressure fuel pump performance test? YES: Refer to the INTERMITTENT CONDITION Symptom (Diagnostic Procedure). NO: Replace the High pressure fuel pump. Perform the POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). See: Verification Tests\Powertrain Verification Test - Ver 1
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