Injector Performance Test

Injector Performance Test

Purpose

This procedure provides the ability to verify the internal component integrity of the 7.3L diesel fuel injectors.

The following Diagnostic Tests must be completed before this procedure:

- Hard Start/No Start or Performance Diagnostic Guides
- KOEO Injector Electrical Self-Test (Buzz Test)
- KOER Cylinder Contribution Test
- Injection Control Pressure (ICP) Test (Oil Aeration)

Recommended Procedure

Note: Testing of new fuel injectors prior to installation in the engine will cause inaccurate test results.

Note: Before removing the suspect fuel injector(s) remove the valve cover(s) and monitor the fuel injector spill spouts for oil flow while the engine is running at idle. The amount of oil flowing through the top of the fuel injector is directly proportional to the amount of fuel flowing out of the tip. If low oil flow is observed at the top of the fuel injector fuel flow out the tip will also be low providing a rough idle condition.






1. Remove the suspect fuel injector. For additional information refer to Fuel Charging and Controls.

2. Inspect the three external fuel injector 0-rings for wear cracks and cuts. The 0- rings may be repaired separately from the injector assembly. Install a new 0 - ring(s) as necessary.

Note: A vacuum pump with a minimum 0 - 28 in Hg gauge is required.

Note: Inspect the three calibrating injector 0-rings for wear cracks and cuts. Install a new 0-ring(s) as necessary. The calibrating injector 0-rings are the same 0-ring utilized by the 7.3L fuel injector.






3. Verify the fuel injector tester and vacuum pump as follows:

a. In stall the calibrating injector adapter into the fuel injector tester and make sure it is properly seated. Use the shouldered fuel injector retaining bolt from the engine and torque the retaining bolt to 13 Nm (120 lb/in).

b. Connect the vacuum pump to the fuel port and apply 25 in Hg of vacuum. Monitor the gauge for 6 minutes. Verify there is no vacuum loss. If vacuum loss is present inspect the fuel injector tester fittings O-rings vacuum hose and vacuum pump for leaks. Repair as necessary and repeat the test.






4. Once the tool function capability has been verified lubricate the 0-rings of the suspect injector with clean engine oil. Install the suspect fuel injector into the fuel injector tester. Use the fuel injector retaining bolts from the engine and torque the retaining bolts to 13 Nm (120 lb/in).


Note: Some fuel injectors may exhibit minimal vacuum loss. Vacuum loss less than 1/2 in Hg is acceptable and does not indicate a damaged fuel injector.

Note: If vacuum loss is noted the vacuum pump must be disconnected before the test can be repeated. The additional application of vacuum without complete removal of the vacuum pump will cause inaccurate test results.

5. Connect the vacuum pump to the fuel port and apply a minimum of 25 in Hg vacuum. Monitor the vacuum gauge for 6 minutes and check for signs of vacuum loss.

- If vacuum loss is between 1/2 - 2 in Hg with no additional loss of vacuum the fuel injector barrel and plunger is scored. Install a new fuel injector.

- If vacuum loss is greater than 1/2 in Hg within 6 minutes the fuel injector is damaged. Install a new fuel injector.

- If vacuum loss is less than 1/2 in Hg leave the vacuum pump connected to the fuel port and GO to step 6.






6. Monitor the vacuum pump while connecting 689 kpa (100 psi) of regulated shop air to the high-pressure oil port. If the vacuum loss is affected by the presence of air pressure the fuel injector is damaged. If no vacuum loss is present GO to step 7.

7. Check for air leaks possibly indicated by whistles or continuous bubbles at the spill port indicating the fuel injector is damaged. If noncontinuous bubbles are present at the spill port the fuel injector is not damaged.

Vacuum loss indicates internal injector scoring which may cause a rough idle or low power concern.

Vacuum loss that is affected by the presence of air pressure on the high-pressure oil side indicates internal 0-ring damage. This 0-ring separates the fuel from the oil and may contribute to excessive oil consumption.

No vacuum loss on the fuel side with an air leak from the high-pressure oil side (top) indicates a damaged poppet valve or seal.

Repeat steps 4 - 7 (calibration of the fuel injector tester is not required) for the remaining suspect fuel injector(s) as necessary.

Tools Required

- Fuel Injector Tester
- Vacuum Pump