Table 1: | Fuel Injector Balance Test Example (Typical) |
The scan tool is first used to energize the fuel pump relay. The fuel injector tester is then used to pulse each injector 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.
Cylinder | 1 | 2 | 3 | 4 |
---|---|---|---|---|
1st Reading | 393 kPa (57 psi) | 393 kPa (57 psi) | 393 kPa (57 psi) | 393 kPa (57 psi) |
2nd Reading | 310 kPa (45 psi) | 296 kPa (43 psi) | 303 kPa (44 psi) | 324 kPa (47 psi) |
Amount of Drop | 83 kPa (12 psi) | 97 kPa (14 psi) | 90 kPa (13 psi) | 69 kPa (10 psi) |
Average Range: 75-95 kPa (10.9-13.8 psi) | Injector OK | Replace fuel injector - too much fuel pressure drop | Injector OK | Replace fuel injector - too little fuel pressure drop |
The number below refers to the step number on the diagnostic table.
Step | Action | Values | Yes | No | ||||
---|---|---|---|---|---|---|---|---|
1 | Did you perform the Diagnostic System Check-Engine Controls? | -- | Go to Step 2 | |||||
2 | Did you perform the Fuel Injector Coil Test? | -- | Go to Step 3 | |||||
Important : DO NOT perform this test if the engine coolant temperature (ECT) is above 94°C (201°F). Observe the ECT Sensor parameter with a scan tool. Is the ECT Sensor parameter less than the specified value? | 94°C (201°F) | Go to Step 4 | -- | |||||
4 |
Important: Verify that adequate fuel is in the fuel tank before proceeding with this diagnostic.
Important:
Is the fuel pressure within the specified range? | 379-427 kPa (55-62 psi) | Go to Step 5 | Go to Fuel System Diagnosis | ||||
5 |
Important: The fuel pressure may vary slightly when the fuel pump stops operating. After the fuel pump stops operating, the fuel pressure should stabilize and remain constant. Monitor the fuel pressure gage for 1 minute. Does the fuel pressure decrease by more than the specified value? | 34 kPa (5 psi) | Go to Fuel System Diagnosis | Go to Step 6 | ||||
6 |
Notice: Do Not repeat any portion of this test before running the engine in order to prevent the engine from flooding.
Important: The fuel pressure may rise after the fuel injector stops pulsing. Record the fuel pressure value immediately after the fuel injector stops pulsing. DO NOT record the higher fuel pressure value. Is the difference between any individual pressure drop and the average pressure drop more than the specified value? | 10 kPa (1.5 psi) | Go to Step 7 | |||||
7 | Perform the Fuel Injector Cleaning . Did you complete the procedure? | -- | Go to Step 8 | -- | ||||
8 | Operate the system in order to verify the repair. Did you correct the condition? | -- | System OK |