Circuit/System Testing

P0087

1. Verify that the engine starts.
   • If engine does not start 

     Refer to Engine Cranks But Does Not Run

   • If engine starts 
2. Verify the following conditions do not exist:
   NOTE: It may be necessary to remove engine components for the visual inspections.
   • Restricted or kinked fuel supply lines that would restrict the flow of fuel
   • Fuel leaks between the fuel tank and the fuel injection pump
   • Fuel leaks in the fuel return lines
     NOTE: A fuel return line that is leaking, is a good indication there is a restriction in the return system.
   • If any leaks or restrictions are present 

     Repair as necessary

   • If no leaks or restrictions are present 
3. Disconnect the supply hose at the G18 High Pressure Fuel Pump.
4. Connect the J-37287  Fuel Line Shut-off Adapter to the supply hose and place the other end of the hose into a suitable container.
5. Ignition ON.
6. Command the fuel pump on for 30 s
7. Verify at least 1200 mL (40.2 oz) of fuel is in the container.
   • If less than 1200 mL (40.2 oz) 
   1. Verify that the fuel filter is not restricted.
      • If the fuel filter is restricted, replace fuel filter.
      • If the fuel filter is not restricted, Replace the G12 Fuel Pump assembly.
   • If greater than 1200 mL (40.2 oz) 
8. Reassemble the supply hose at the G18 High Pressure Fuel Pump.
9. Engine running.
10. Verify the scan tool Fuel Rail Pressure Sensor and the Desired Fuel Rail Pressure parameters closely match.
    • If the parameters do not closely match 

      Refer to Fuel System Diagnosis - High Pressure Side .

    • If the parameters closely match 
11. All OK

P0088

1. Engine at idle.
   NOTE: At engine start, fuel pressure regulator 2 controls fuel pressure at idle. The engine will remain in this mode if the fuel temperature is below 15°C (59°F) or until fuel pressure regulator 2 adapts (which occurs at higher engine loads) or until fuel temperature reaches 60°C (140°F). Once the adaptation is complete, the vehicle will use fuel pressure regulator 1 to control rail pressure.
2. Fuel temperature must be greater than 15°C (59°F)
3. Using the scan tool, command the Fuel Rail Pressure to 60 MPa (8702 psi) for 15 seconds. This allows the Q18B Fuel Pressure Regulator 2 adaptation process to complete.
4. Engine at a stable idle.
5. Command the fuel pressure incrementally through the entire fuel pressure range with a scan tool.
   NOTE: When commanding fuel rail pressure at idle the maximum achievable pressure will be approximately 60 MPa (8702 psi).
6. Verify the scan tool Fuel Rail Pressure Sensor and the Desired Fuel Rail Pressure parameters are within 690 kPa (100 psi) for the entire fuel pressure range and note results.
   • If the parameters are not within 690 kPa (100 psi) 

     Replace the Q18A Fuel Pressure Regulator 1.

   • If the parameters are within 690 kPa (100 psi) 
7. All OK