Circuit/System Verification
- Repair all fuel system related DTCs, except P2635, before performing this diagnostic.
- Inspect the fuel system for damage or external leaks before proceeding.
- Verify the fuel tank is not empty before proceeding.
- The fuel pump may need to be commanded On a few times in order to obtain the highest possible fuel pressure.
- Do NOT perform the Fuel System Diagnosis if the engine coolant temperature is above 60°C (150°F). High fuel pressure readings may result due to hot soak fuel boiling. With the engine Off, the fuel pressure may increase beyond the pressure relief regulator valve's setting point of 690 kPa (100 PSI) ± 5%.
- Ignition - On/Vehicle - In Service Mode & Engine - Off
- Perform the scan tool control function: Fuel Pump Enable - On - Command the function On several times.
Verify the scan tool parameter: Fuel Pressure Sensor = 345 to 650 kPa (50 to 94 PSI) - While the fuel pump is running.
- If less than 345 kPa (50 PSI)
Refer to: Circuit/System Testing - Fuel Pressure Low
- If greater than 650 kPa (94 PSI)
Test or replace the component: G12 Fuel Pump
- Go to next step: If between 345 and 650 kPa (50 and 94 PSI)
- If less than 345 kPa (50 PSI)
- Verify the scan tool parameter: Fuel Pressure Sensor = Pressure should decrease to less than 600 kPa (87 PSI) after the fuel pump is turned Off.
- If greater than 600 kPa (87 PSI)
Test or replace the component: G12 Fuel Pump
- Go to next step: If less than 600 kPa (87 PSI)
- If greater than 600 kPa (87 PSI)
- Verify the scan tool parameter: Fuel Pressure Sensor = Pressure drops less than 34 kPa (5 PSI) within 1 min.
- If the pressure drops 34 kPa (5 PSI) or greater
Refer to: Circuit/System Testing - Fuel Pressure Leaks Down
- Go to next step: If the pressure drops less than 34 kPa (5 PSI)
- If the pressure drops 34 kPa (5 PSI) or greater
- Ignition On - Engine Running
- Verify the scan tool parameter: Fuel Pressure Sensor = 300 to 400 kPa (43 to 58 PSI)
- If less than 300 kPa (43 PSI)
Refer to: Circuit/System Testing - Fuel Pressure Low
- If greater than 400 kPa (58 PSI)
Test or replace the component: G12 Fuel Pump
- Go to next step: If between 300 and 400 kPa (43 and 58 PSI)
- If less than 300 kPa (43 PSI)
- Verify the scan tool parameter: Short Term Fuel Pump Trim & Long Term Fuel Pump Trim = The product should be less than 1.5 when both parameters are multiplied together.
- If 1.5 or greater
Refer to: Circuit/System Testing - Fuel Pressure Low
- Go to next step: If less than 1.5
- If 1.5 or greater
- Perform the scan tool control function: Fuel Pressure - Increase - 300 kPa (43.5 PSI)
The pressure should not drop off during acceleration, cruise or hard cornering.
- Verify the following parameters are within 45 kPa (6.5 PSI) of each other:
- Desired Fuel Pressure
- Fuel Pressure Sensor
- If greater than 45 kPa (6.5 PSI)
Refer to: Circuit/System Testing - Fuel Pressure Drops Off
- Go to next step: If less than 45 kPa (6.5 PSI)
- Perform the scan tool control function: Fuel Pressure - Increase - 400 kPa (58 PSI)
The pressure should not drop off during acceleration, cruise or hard cornering.
- Verify the following parameters are within 60 kPa (8.7 PSI) of each other:
- Desired Fuel Pressure
- Fuel Pressure Sensor
- If greater than 60 kPa (8.7 PSI)
Refer to: Circuit/System Testing - Fuel Pressure Drops Off
- Go to next step: If less than 60 kPa (8.7 PSI)
- Perform the following procedure/test: Fuel Injector Diagnosis
Verify the procedure/test passes.
- If the procedure/test does not pass
Replace the component that failed the test: Q17 Fuel Injector
- Go to next step: If the procedure/test passes
- If the procedure/test does not pass
- Refer to: Symptoms - Engine Controls