P0093-FUEL RAIL PRESSURE MALFUNCTION LARGE LEAK DETECTED





For a complete wiring diagram Refer to Section 8W


  • When Monitored:

    With the engine running.

  • Set Condition:

    The ECM determines that the fuel system has a high-side (pressure) or low-side (vacuum) leak.


Possible Causes
  
AIR IN FUEL SYSTEM
  
FUEL DELIVERY SYSTEM CONCERNS
  
FUEL INJECTOR(S)
  
FUEL PRESSURE SOLENOID
  
FUEL PUMP
  
FUEL SYSTEM CONTAMINATION
  
FUEL SYSTEM LEAK
  



Diagnostic Test

1.CHECKING FOR OTHER ECM DTCS

WARNING: HIGH-PRESSURE FUEL LINES DELIVER DIESEL FUEL UNDER EXTREME PRESSURE FROM THE INJECTION PUMP TO THE FUEL INJECTORS. THIS MAY BE AS HIGH AS 23,200 PSI (1600 BAR). USE EXTREME CAUTION WHEN INSPECTING FOR HIGH-PRESSURE FUEL LEAKS.


WARNING: FUEL UNDER THIS AMOUNT OF PRESSURE CAN PENETRATE SKIN CAUSING PERSONAL INJURY OR DEATH. INSPECT FOR HIGH-PRESSURE FUEL LEAKS WITH A SHEET OF CARDBOARD. WEAR SAFETY GOGGLES AND ADEQUATE PROTECTIVE CLOTHING WHEN SERVICING FUEL SYSTEM.





Are there any other DTCs present?

Yes


No
  • Go To2

2.CURRENT DTC

NOTE: If the ECM detects and stores a DTC, the ECM also stores the engine/vehicle operating conditions under which the DTC was set. Some of these conditions are displayed on the scan tool at the same time the DTC is displayed.


NOTE: Before erasing stored DTCs, record these conditions. Attempting to duplicate these conditions may assist when checking for an active DTC.


NOTE: Refer to the Service Information and perform the Air Bleed Procedure before continuing diagnosis.




NOTE: Driving the vehicle up and down steep hills or rapid cornering with a low fuel level can cause this DTC to set. Verify with customer if Low Fuel Light was illuminated when fault occurred.





Does the scan tool display this DTC?

Yes
  • Go To3


No

3.FUEL SYSTEM LEAK


WARNING: HIGH-PRESSURE FUEL LINES DELIVER DIESEL FUEL UNDER EXTREME PRESSURE FROM THE INJECTION PUMP TO THE FUEL INJECTORS. THIS MAY BE AS HIGH AS 23,200 PSI (1600 BAR). USE EXTREME CAUTION WHEN INSPECTING FOR HIGH-PRESSURE FUEL LEAKS.


WARNING: FUEL UNDER THIS AMOUNT OF PRESSURE CAN PENETRATE SKIN CAUSING PERSONAL INJURY OR DEATH. INSPECT FOR HIGH-PRESSURE FUEL LEAKS WITH A SHEET OF CARDBOARD. WEAR SAFETY GOGGLES AND ADEQUATE PROTECTIVE CLOTHING WHEN SERVICING FUEL SYSTEM.



NOTE: This vehicle is not equipped with an in-tank fuel lift pump. The high pressure fuel pump draws (vacuums) the fuel from the fuel tank. Even a very small leak in the fuel supply system between the fuel tank and high-pressure pump can cause driveability problems and dtc's to set.



Is there any evidence of leakage?

Yes


No
  • Go To4

4.FUEL SYSTEM CONTAMINATION

NOTE: Mixing any other fuels such as gasoline or kerosine can cause this DTC to set.



WARNING: HIGH-PRESSURE FUEL LINES DELIVER DIESEL FUEL UNDER EXTREME PRESSURE FROM THE INJECTION PUMP TO THE FUEL INJECTORS. THIS MAY BE AS HIGH AS 23,200 PSI (1600 BAR). USE EXTREME CAUTION WHEN INSPECTING FOR HIGH-PRESSURE FUEL LEAKS.


WARNING: FUEL UNDER THIS AMOUNT OF PRESSURE CAN PENETRATE SKIN CAUSING PERSONAL INJURY OR DEATH. INSPECT FOR HIGH-PRESSURE FUEL LEAKS WITH A SHEET OF CARDBOARD. WEAR SAFETY GOGGLES AND ADEQUATE PROTECTIVE CLOTHING WHEN SERVICING FUEL SYSTEM.




Is the fuel contaminated?

Yes


No
  • Go To5

5.ATTEMPT TO START ENGINE





Does the engine start and idle?

Yes
  • Go To6


No

6.CHECKING FOR AIR IN FUEL SYSTEM



NOTE: If there is air in the fuel system, the Actual Fuel Pressure will oscillate more than 100 psi above and/or below the Fuel Pressure Setpoint.



Does Actual Fuel Pressure oscillate more than 100 psi above and/or below the Fuel Pressure Setpoint?

Yes


No
  • Go To7

7.FUEL PRESSURE SOLENOID



NOTE: A sticking Fuel Pressure Solenoid is indicated by Actual Fuel Pressure gradually dropping below the Fuel Pressure Setpoint then suddenly increasing (spiking) above the Fuel Pressure Setpoint.



Does Actual Fuel Pressure gradually decrease then suddenly increase (spike) above the Fuel Pressure

Yes


No
  • Go To8

8.CHECKING FUEL DELIVERY SYSTEM


NOTE: The following is a list of problems that can cause fuel pressure to deviate from specification: restricted fuel filter or fuel lines, failed fuel pressure solenoid, air in fuel system, failed fuel sending unit, contaminated fuel, faulty injector.


NOTE: This vehicle is not equipped with an in-tank fuel lift pump. The high pressure fuel pump draws (vacuums) the fuel from the fuel tank. Even a very small leak in the fuel supply system between the fuel tank and high-pressure pump can cause driveability problems and dtc's to set.



Were there any problems with the Fuel Delivery System?

Yes


No
  • Go To9

9.FUEL INJECTOR(S)

NOTE: An injector that sticks open can cause this DTC. A sticking injector will cause the engine to misfire and emit excessive black smoke from the exhaust system.




Does the engine exhibit the symptoms described in the above note?

Yes
  • Using the Service Information, remove and inspect the Fuel Injectors for signs of damage or debris that may cause the injector to stick. Sticking injectors may cause the combustion chamber to become black and oil soaked. Replace Injector(s) as necessary.
  • Perform the ECM Verification Test Ver. 1 (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING).


No

10.FUEL PRESSURE SOLENOID








Does the ECM display this DTC?

Yes


No
  • Test Complete.

11.CHECKING FUEL DELIVERY SYSTEM


NOTE: The following is a list of problems that can cause fuel pressure to deviate from specification: restricted fuel filter or fuel lines, failed fuel pressure solenoid, air in fuel system, failed fuel sending unit, contaminated fuel, faulty injector.



Were there any problems with the Fuel Delivery System?

Yes


No

12.FUEL PRESSURE SOLENOID








Does the ECM display this DTC?

Yes


No
  • Test Complete.

13.FUEL QUANTITY SOLENOID








Did this DTC set again?

Yes


No
  • Test Complete.