Checking The Fuel Delivery System

CHECKING THE FUEL DELIVERY SYSTEM

Special Tools:

For a complete wiring diagram, refer to the Wiring Information.

WARNING: Follow these safety precautions to reduce the risk of fire and possible serious or fatal injury when performing this test procedure.
- Fuel or fuel vapors are highly flammable. A fire could occur if an ignition source is present. Do not expose the fuel or the test equipment used in this procedure to open flames or sparks.
- Inhalation of fuel vapors could lead to disorientation and personal injury. Keep the service area well ventilated, or perform this test procedure in an area where there is a building exhaust removal system.
- Relieve fuel system pressure before servicing fuel system components.
- Use extreme caution when connecting and disconnecting fuel lines.
- Considerable fuel leakage may occur when servicing the fuel system. Wear protective eyewear and clothing to protect from fuel splash, and take suitable fuel containment measures.
- Wrap a shop towel around the fuel pressure gauge connection to absorb fuel leakage that occurs when connecting the test equipment. Place the towel in an approved container when complete.
- Never store fuel in an open container due to the possibility of fire or explosion. Have a dry chemical (Class B) fire extinguisher nearby.
- High-pressure fuel lines deliver diesel fuel under extreme pressure from the injection pump to the fuel injectors. This may be as high as 26,107 psi (1800 bar). Use extreme caution when inspecting for high-pressure fuel leaks. Fuel under this amount of pressure can penetrate skin causing possible serious or fatal injury.

1. VISUALLY CHECK THE FUEL DELIVERY SYSTEM FOR LEAKS AND DAMAGE

NOTE: Make sure that both Batteries are fully charged before proceeding. A weak battery can cause inaccurate fuel volume readings.

1. Turn the ignition off.
2. Visually inspect the Fuel Delivery System for external leaks and damage.
3. Visually inspect the Fuel tank vents and hoses for any signs of a possible restriction or plugging.

Is the system leaking, plugged, or damaged?

Yes

- Repair/replace as necessary.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

No

- Go To 2

2. CHECKING FUEL QUALITY/CONTAMINATION
1. Check the quality of the fuel using the DIESEL FUEL CONTAMINATION TEST PROCEDURE. Diesel Fuel Contamination Testing Procedure

Were any signs of contamination detected?

Yes

- Perform the appropriate repair according to the testing and cleaning procedure.
- Go To 3

No

- Go To 3

3. IN-TANK FUEL LIFT PUMP FLOW TEST WITH DECAY TESTER

NOTE: Before performing the IN-TANK FUEL LIFT PUMP FLOW test, verify that the fuel level in the fuel tank is above 1/4 full. If fuel tank is not above 1/4 full the pump will take in air causing the test results to be inaccurate.

1. Disconnect the low pressure fuel supply line from the High Pressure Fuel Pump. Connect the (8978A) to the low pressure fuel supply line.

WARNING: To reduce the risk of fire and serious possible serious or fatal injury, place the Reservoir Assembly 534960 (3) on the floor and out of the way so that it is not a trip hazard.

2. Perform the following to purge air from the system:
- With the scan tool, actuate the In-Tank Fuel Lift Pump Module.
- Open the Flow Test Valve and allow the fuel to flow into the Reservoir for 10 seconds, then close the Flow Test Valve.
- Turn the ignition off.
- Disconnect, empty, and then reconnect the Reservoir Assembly.

3. Perform the following three times to find the average flow rate:
- With the scan tool, actuate the In-Tank Fuel Lift Pump Module.
- Open the Flow Test Valve (1) for 10 seconds, then close the Valve.
- Turn the ignition off.
- Measure and record the amount of fuel in the Reservoir Assembly.
- Disconnect, empty, and then reconnect the Reservoir Assembly.

4. Add the three recorded measurements and then divide the total by three to calculate the average flow rate. The flow rate is 500 ml in 10 seconds.

Does the average flow rate meet or exceed the specification?

Yes - Vehicle starts and runs:

- Go To 5

Yes - Vehicle is a no start:

- Go To 10

No

- Leave the Fuel Decay Tester installed. Replace the Fuel Filter/Water Separator. During Fuel Filter replacement, be sure to check and clean the secondary filter screen in the filter head outlet.
- Go To 4

4. RECHECK IN-TANK FUEL LIFT PUMP FLOW
1. Perform the following to purge air from the system:
- With the scan tool, actuate the In-Tank Fuel Lift Pump Module.
- Open the Flow Test Valve (1) for 10 seconds, then close the Valve.
- Turn the ignition off.
- Disconnect, empty, and then reconnect the Reservoir Assembly (2).

2. Perform the following three times to find the average flow rate:
- With the scan tool, actuate the In-Tank Fuel Lift Pump Module.
- Open the Flow Test Valve (1) for 10 seconds, then close the valve.
- Turn the ignition off.
- Measure and record the amount of fuel in the Reservoir Assembly (2).
- Disconnect, empty, and then reconnect the Reservoir Assembly (2).

3. Add the three recorded measurements and then divide the total by three to calculate the average flow rate. The flow rate is 500 ml in 10 seconds.

Does the average flow rate meet or exceed the specification?

Yes

- Repair complete.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

No

- Use the wiring diagram as a guide to check the In-Tank Fuel Lift Pump wiring for an open, high resistance, or short to ground. If the In-Tank Fuel Lift Pump wiring is okay, remove the fuel tank and replace the In-Tank Fuel Lift Pump Module.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

5. PRESSURE LIMITING VALVE

NOTE: In the illustration provided, the pressure-limiting valve location is indicated by the number (1).

1. Reconnect the fuel supply hose.
2. Remove the banjo bolt from the Pressure Limiting Valve on the fuel rail.
3. Install the (9012)into the Pressure Limiting Valve.
4. Attach one end of a fuel hose to the fuel fitting and put the other end of the fuel hose into a container.

NOTE: NOTE: Do not drive the vehicle with any portion of this test kit installed.

5. Start the engine and operate the engine at idle. Watch for fuel flow into the fuel container.

NOTE: There should be no fuel flow into the container.

6. While the engine is at idle, actuate the Fuel Pressure Override Test with the scan tool. Watch for fuel flow into the fuel container.

NOTE: You may observe a few dribbles of fuel from Pressure Limiting Valve during Fuel Pressure Override Test. One drop per second or 8 ml in 30 seconds is considered normal. Do not replace this valve unless you can see continuous leak.

Is fuel flowing into the container?

Yes

- Replace the Pressure Limiting Valve.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

No

- Go To 6

6. ENGINE RUNNING INJECTOR RETURN FLOW TEST

NOTE: The purpose of this test is to determine if the Fuel Injectors are leaking internally into the fuel return.

1. Turn the engine off.
2. Remove the (9012) from the Pressure Limiting Valve.
3. Operate the engine until the coolant temperature is above 82.2°C (180°F).
4. Turn the engine off.
5. Remove the banjo connector from the fuel drain tube at the rear of the fuel filter housing.
6. Install the (9012) in place of the banjo connector.

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

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

NOTE: This hose will be used to measure the High Pressure Pump return flow in the next test procedure.

8. Remove the vehicle fuel return line (Quick connect) from the engine fuel drain tube.
9. 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.

10. Start engine and allow to idle for 30 seconds. This step allows the flows to stabilize.
11. 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.

12. Press the Run button to start the Fuel Pressure Override Test. The engine speed will elevate rapidly to 1200 RPM and the rail pressure will increase to 26107 psi (1800 bar). At this point, move (Hose B) from the bucket and insert it into a graduated cylinder. Collect the fuel until the Fuel Pressure Override Test times out (30 seconds).
13. Measure and record the amount of fuel collected in the graduated cylinder. Repeat this three times and take the average of the three results.

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

14. 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 10 through 13 as a guide. Continue on to next step.
15. 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 10 through 13 as a guide. Repeat this procedure for injectors 2-6. Continue on to next step.
16. 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

- Go To 7

No

- Perform the necessary repairs and verify fuel system operation.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

7. HIGH PRESSURE DELIVERY PUMP RETURN FLOW TEST
1. Move (Hose B) back into the fuel container.
2. Empty the graduated cylinder.
3. Move (Hose A) into the graduated cylinder.
4. Allow the engine to idle for one minute while collecting the fuel from (Hose A).
5. Measure the amount of fuel collected from (Hose A) in the graduated cylinder.

NOTE: The fuel flow should be less than 1,150 ml/minute at idle.

Is the flow less than 1,150 ml/minute at idle?

Yes

- Go To 8

No

- Replace the High Pressure Delivery Pump.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

8. HIGH PRESSURE DELIVERY PUMP PERFORMANCE TEST
1. Turn the engine off.
2. Remove the (9012) and reinstall the banjo connector.
3. Disconnect the Fuel Control Actuator harness connector.
4. Disconnect high pressure fuel line from the fuel rail and route the high pressure fuel line into a graduated cylinder.
5. Crank the engine until fuel exits this line. This will not be high pressure fuel.
6. Crank the engine for three 10 second intervals.

NOTE: This will give you 30 total seconds of flow time. These are broken into three separate intervals to prevent damage to the starter.

7. Fuel flow specification's based on engine cranking speed. If you do not collect the stated amount of fuel in 30 seconds, replace the pump:
- Minimum fuel pump flow at 150 RPM cranking speed is 70mL.
- Minimum fuel pump flow at 200 RPM cranking speed is 90mL.

Does the fuel flow exceed the minimum specification?

Yes

- Go To 9

No

- Replace the High Pressure Delivery Pump.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

9. CHECKING THE FUEL CONTROL ACTUATOR
1. Reconnect the Fuel Control Actuator harness connector.
2. Reconnect all fuel lines and hoses.
3. Start the engine.
4. With the scan tool, navigate to Systems Tests and select the Fuel Pressure Override Test.
5. Allow the engine speed and fuel pressure to ramp up and stabilize and then stop actuation.

Does the engine speed and fuel pressure ramp up and stabilize when actuated and then come back to rest at idle and stabilize when actuation is stopped?

Yes

- The fuel system is operating normally. Check for any Service Bulletins that may apply.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

No

- Replace the Fuel Control Actuator.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

10. PRESSURE LIMITING VALVE (NO START)