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. Before the Fuel Injector Balance Test is started, the electrical connector should be tested using a Noid Lite.
a. Disconnect electrical connectors at fuel injectors.
b. Connect a Noid Lite to the female connector.
c. Crank the engine.
d. If the Noid Lite does not blink, the electrical problem must be corrected before continuing.
e. Remove noid lights and install connectors on injectors.
2. Remove air cleaner inlet tube.

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.

3. Connect Scan Tool and turn ignition On.
4. Relieve fuel system pressure. (Refer to "Relieving Fuel Pressure" procedure.) Service and Repair
5. Energize fuel pump. (Refer to "Energizing Fuel Pump" procedure.) Component Tests and General Diagnostics
6. Ensure that fuel pressure is between 345-414 kPa (50-60 psi) (1st Reading).




7. Using the Scan tool pulse the #1 injector. (Refer to "Scan Tool - Special Tests" procedure.)
8. Record pressure at the instant the gauge needle stops moving (2nd reading).
9. Repeat steps 6 through 8 for the remaining three injectors.

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

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