The scan tool first energizes the fuel pump and then the injectors for a precise amount of time allowing a measured amount of fuel into the manifold. This causes a drop in system fuel pressure that can be recorded and used to compare each injector.
The numbers below refer to the step numbers in the diagnostic table.
Caution: Wrap a shop towel around the fuel pressure connection in order to reduce the risk of fire and personal injury. The towel will absorb any fuel leakage that occurs during the connection of the fuel pressure gage. Place the towel in an approved container when the connection of the fuel pressure gage is complete.
The engine coolant temperature must be below the operating temperature in order to avoid irregular fuel pressure readings due to Hot Soak fuel boiling.
Tests the fuel system for the ability to reach a specified fuel pressure range.
Tests the fuel system for the ability to maintain a specified fuel pressure range.
If the pressure drop value for each fuel injector is within 10 kPa (1.5 psi) of the average pressure drop value, the fuel injectors are flowing properly. Calculate the pressure drop value for each fuel injector by subtracting the second pressure reading from the first pressure reading.
Step | Action | Values | Yes | No |
---|---|---|---|---|
1 | Did you perform the Powertrain On-Board Diagnostic (OBD) System Check? | -- | ||
2 | Did you perform the Fuel Injection Coil Test? | -- | Go to Fuel Injector Solenoid Coil Test - Engine Coolant Temperature Between 10-35 Degrees C (50-95 Degrees F) or Fuel Injector Solenoid Coil Test - Engine Coolant Temperature Outside 10-35 Degrees C (50-95 Degrees F) | |
Important : Do not perform this test if the engine coolant temperature is above 94°C (201°F). Install a scan tool. Does the scan tool indicate that the ECT parameter is less than the specified value? | 94°C (201°F) | -- | ||
Caution: Wrap a shop towel around the fuel pressure connection in order to reduce the risk of fire and personal injury. The towel will absorb any fuel leakage that occurs during the connection of the fuel pressure gage. Place the towel in an approved container when the connection of the fuel pressure gage is complete.
Important: The fuel pump will run for approximately 2 seconds. Repeat as necessary in order to achieve the highest possible fuel pressure. Does the fuel pressure measure within the specified value? | 333-376 kPa (48-55 psi) | Go to Fuel System Diagnosis | ||
After the fuel pump stops, the fuel pressure may vary slightly, then should hold steady. Does the fuel pressure remain constant within the specified value? | 333-376 kPa (48-55 psi) | Go to Fuel System Diagnosis | ||
Does any fuel injector have a pressure drop value that is either higher than the average pressure drop or lower than the average pressure drop by the specified value? | 10 kPa (1.5 psi) | Go to Symptoms | ||
7 | Perform the Fuel Injector Cleaning . Did you complete the procedure? | -- | -- | |
8 | Operate the system in order to verify the repair. Did you correct the condition? | -- | System OK | Go to Symptoms |