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Injector Return Flow Test






INJECTOR RETURN FLOW TEST

1. ENGINE RUNS

NOTE: Review Warranty bulletin D-05-24.

NOTE: Battery charger may need to be utilized if cranking speed is below 170 RPMs.

Does the engine run?

Yes

- Go To 2

No

- Go To 3

2. INJECTOR RETURN FLOW TEST @ 1200 RPM AND 1800 BAR RAIL PRESSURE
1. Operate the engine until the coolant temperature is above 82.2°C (180° F).
2. Turn the engine off.
3. Remove the banjo connector from the fuel drain tube at the rear of the fuel filter housing.
4. Install fuel system test fitting 9012 in place of the banjo connector.

NOTE: Do not use test fitting 9014. This fitting will block return flow from the High Pressure Delivery Pump and damage the seal and could potentially damage the engine.

5. Install a 5/16 diameter rubber fuel hose (Hose A) onto the test fitting and into a fuel container.

NOTE: This hose is used to measure the High Pressure Pump return flow.

6. Remove the vehicle fuel return line (Quick connect) from the engine fuel drain tube.
7. Install a 5/16 diameter rubber fuel hose (Hose B) onto the engine fuel drain tube and into the fuel container.

NOTE: This hose will be used to measure the Injector return flow for this procedure.

8. Start engine and allow to idle for 30 seconds. This step allows the flows to stabilize.
9. Using the scan tool, navigate to ECM view -> PCM Cummins -> More Options-> System Tests -> Fuel Pressure Override Test. Select Start, then press Next.

NOTE: While the test is running, record the FCA duty cycle % and actual rail pressure. Record the readings on the Cummins Diesel Diagnostic Worksheet located under e-files, service, Star center in Dealerconnect.

10. As you press the Run button to start the Fuel Pressure Override Test, move (Hose B) from the bucket and insert it into a graduated cylinder. The engine speed will elevate rapidly to 1200 RPM and the rail pressure will increase to 26107 psi (1800 bar). Collect the fuel until the Fuel Pressure Override Test times out (30 seconds).
11. Measure and record the amount of fuel collected in the graduated cylinder.

NOTE: Flow should be less than 210 ml for 30 seconds.

12. If the flow is less than 210 ml/30 seconds, the test has successfully passed. If the flow is greater than 210 ml/30 seconds, turn off the engine and remove all 6 high pressure fuel lines. Re-torque the high-pressure connector nut for each injector. Inspect for damage, repair/replace as necessary. Reinstall the high pressure fuel lines. Re-measure the injector return flow using steps 8 through 12 as a guide. Continue on to next step.
13. If the amount of fuel is still greater than 210 ml/30 seconds after re-torquing the high-pressure connector nuts, turn the engine off and remove the #1 high pressure fuel line. Cap the #1 fuel port using tool 9864 for the 6.7L engine on the fuel rail and re-measure the injector return flow using steps 8 through 12 as a guide. Repeat this procedure for injectors 2-6. Continue on to next step.
14. Replace the Fuel Injector and High pressure connector of the injector that shows the largest amount of change when capped off.

Did the vehicle pass the Injector Return Flow test at step 12 without any repairs needed?

Yes

- Injector return flow is within specification, and no repair is needed.

No

- Replace the failed Fuel Injector(s) and verify repair.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

3. INJECTOR RETURN FLOW TEST DURING ENGINE CRANKING @200 RPM WHEN THE VEHICLE WILL NOT START
1. Remove the banjo connector from the fuel drain tube at the rear of the fuel filter housing.
2. Install fuel system test fitting 9012 in place of the banjo connector.

NOTE: Do not use test fitting 9014. This fitting will block return flow from the High Pressure Delivery Pump and damage the seal and could potentially damage the engine.

3. Install a 5/16 diameter rubber fuel hose (Hose A) onto the test fitting and into a fuel container.

NOTE: This hose is used to measure the High Pressure Pump return flow.

4. Remove the vehicle fuel return line (Quick connect) from the engine fuel drain tube.
5. Install a 5/16 diameter rubber fuel hose (Hose B) onto the engine fuel drain tube and into the fuel container. Make sure test lines are straight and slope downward their entire length. This is to avoid trapping air/fuel in the lines while testing.

NOTE: This hose will be used to measure the Injector return flow for this procedure.

6. Unplug the injector harnesses at the valve cover, unplug the harness connector to the FCA.
7. Crank the engine for least 10 seconds until fuel starts to flow out of the pump and injector return hoses. Turn Key off when finished.
8. Let all the fuel drain out of each line before continuing.
9. Place (Hose B)into a graduated cylinder.
10. Crank the engine for 10 seconds (Go from Key off to Crank back to Key off). Do not leave the ignition on between tests.
11. Let all of the fuel drain out of the injector hose.
12. Record the amount of injector return flow for a 10 second crank.

NOTE: Flow should be less than 40 ml for 10 seconds of cranking.

13. If the flow is less than 40 ml, the test has successfully passed. If the flow is greater than 40 ml, remove all 6 high pressure fuel lines and re-torque the high-pressure connector nut for each injector. Inspect for damage, repair/replace as necessary. Reinstall the high pressure fuel lines. Re-measure the injector return flow using steps 7 through 12 as a guide. Go To 14.
14. If the amount collected is still greater than 40 ml, remove the #1 high pressure fuel line. Cap the #1 fuel port using tool 9864 for the 6.7L engine on the fuel rail and re-measure the injector return flow using steps 7 through 12 as a guide. Go To 15.
15. If the amount collected is less than 40 ml for 10 seconds after capping the #1 fuel port, remove and replace the #1 Fuel Injector and #1 High pressure connector. If the amount of fuel collected is still greater than 40 ml after capping the #1 fuel port, repeat step 14 for injectors 2-6.

SPECIFICATION: Less than 40 ml total fuel return flow for 10 seconds. Did the vehicle pass the Injector Return Flow test at step 12 without any repairs needed?

Yes

- Injector return flow is within specification, and no repair is needed.

No

- Replace the failed Fuel Injector(s) and verify repair.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

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