8 - Fuel Injector Balance Test

CAUTION: DO NOT ALLOW SMOKING OR THE USE OF OPEN FLAMES IN THE AREA WHERE WORK ON THE FUEL SYSTEM IS TAKING PLACE. ANYTIME THE FUEL SYSTEM IS BEING WORKED ON, DISCONNECT THE NEGATIVE BATTERY CABLE, EXCEPT FOR THOSE TESTS WHERE BATTERY VOLTAGE IS REQUIRED.

IMPORTANT: If engine is at operating temperature, allow a 10 minute cool down period.

1. Diagnose any fuel injector low or high voltage circuit fault DTCs first. A circuit fault will cause an inoperative fuel injector.

CAUTION: WHENEVER FUEL LINE FITTINGS ARE LOOSENED OR DISCONNECTED, WRAP A SHOP CLOTH AROUND FITTING WHILE CONNECTING GAUGE, TO COLLECT FUEL. PLACE THE CLOTH IN AN APPROVED CONTAINER.




2. Relieve fuel system pressure by using Scan tool to command FUEL PUMP RELAY Off with engine running. Run engine until a stall condition occurs then keep ignition on.
3. Connect fuel pressure gauge to the fuel line test port.
4. Disconnect all four fuel injector harness connectors.
5. Energize fuel pump by using Scan tool to command FUEL PUMP RELAY On for 5 seconds. Then command FUEL PUMP RELAY Off.
6. Ensure fuel rail pressure is between 345-414 kPa (50-60 psi). Refer to "Fuel System Diagnosis - Fuel Supply Chart" if fuel pressure is not within range. Testing and Inspection
7. Connect SA9182E to fuel injector to be tested.
8. Using SA9182E, pulse fuel injector to be tested. Note fuel pressure at the instant the gauge needle stops.

IMPORTANT: Determine the most common pressure reading for all four cylinders after each flow test was performed. This will be the value used to determine if another injector is not working properly. All injectors should be within +/-10 kPa (+/-1.5 psi) from the most common reading.

9. Repeat Steps 5-8 for each injector.
10. Disconnect SA9182E for the fuel injectors.
11. Connect all fuel injector electrical connectors.
12. Start and idle engine to clear raw fuel from cylinders.
13. Connect Scan tool and turn ignition On.
14. Relieve fuel system pressure. (Refer to "Fuel System Pressure Relief" procedure.) Service and Repair
15. Energize fuel pump. (Refer to "Energizing the Fuel Pump" procedure.) Procedures
16. Use Scan tool to perform fuel injector balance test.

Example:

17. Ensure that fuel pressure is between 345-414 kPa (50-60 psi) (1st Reading).
18. Record pressure at the instant the gauge needle stops moving (2nd reading).
19. Repeat steps 6 through 8 for the remaining three or five injectors for 4-cylinder or 6-cylinder engines.

NOTE: The engine must be started after four cylinders have been tested to prevent flooding or internal damage.

20. Add all the 2nd Readings together and divide by 4 (this is the 2nd reading Average).
21. Subtract Average of 2nd Reading from each 2nd Reading to obtain the Difference.
22. An injector is faulty if the Difference is greater than 10 kPa (± 1.5 psi).
23. Check that all fuel injector connectors are connected. Pull back to ensure a positive engagement.
24. Remove fuel gauge bar adapter from fuel pressure test port and recap it.
25. Install air cleaner inlet tube.
26. Start engine and check for leaks.

IMPORTANT: If engine is at operating temperature, allow a 10 minute cool down period.

27. Diagnose any fuel injector low or high voltage circuit fault DTCs first. A circuit fault will cause an inoperative fuel injector.

CAUTION: WHENEVER FUEL LINE FITTINGS ARE LOOSENED OR DISCONNECTED, WRAP A SHOP CLOTH AROUND FITTING WHILE CONNECTING GAUGE, TO COLLECT FUEL. PLACE THE CLOTH IN AN APPROVED CONTAINER.

28. Relieve fuel system pressure by using Scan tool to command FUEL PUMP RELAY Off with engine running. Run engine until a stall condition occurs then keep ignition on.
29. Connect fuel pressure gauge to the fuel line test port.
30. Energize fuel pump by using Scan tool to command FUEL PUMP RELAY On for 5 seconds. Then command FUEL PUMP RELAY Off.
31. Ensure fuel rail pressure is between 345-414 kPa (50-60 psi). Refer to "Fuel System Diagnosis - Fuel Supply Chart", if fuel pressure is not within range. Testing and Inspection

NOTE: The ECM will automatically energize the fuel pump for 1 second between each different fuel injector flow test. Also, the ECM will allow two flow tests per injector unless the engine has been started and ran for longer than 5 seconds.

32. Using Scan tool, perform a FUEL INJECTOR FLOW test for each individual injector. Note the fuel pressure reading AFTER each injector has been pulsed.

IMPORTANT: Determine the most common pressure reading for all four cylinders after each how test was performed. This will be the value used to determine if another injector is not working properly. All injectors should be within +/-10 kPa (+/-1.5 psi) from the most common reading.

33. Start engine and allow to run in order to clear raw fuel from cylinders.