In-Tank Fuel Lift Pump Flow/Diagnostic Test Procedure

IN-TANK FUEL LIFT PUMP FLOW/DIAGNOSTIC TEST PROCEDURE

For a complete wiring diagram refer to the Wiring Information Electrical Diagrams.

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.

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. CHECK LOW PRESSURE FUEL DELIVERY SYSTEM FOR LEAKS AND DAMAGE

WARNING: The fuel system is under a constant pressure (even with the engine off). Before testing or servicing any fuel system hose, fitting, or line, the fuel system pressure must be released. Failure to follow these instructions can result in possible serious or fatal injury.

CAUTION: Troubleshoot all active DTCs before performing this test.

1. Turn the ignition off.
2. Visually and physically inspect the low pressure fuel delivery system for external leaks and damage.

Is the system leaking or damaged?

Yes

- Repair / replace as necessary.
- Perform the ECM VERIFICATION TEST. Powertrain Verification Test

No

- Go to 2

2. CHECK BATTERIES FOR LOW VOLTAGE CONDITION

WARNING: The fuel system is under a constant pressure (even with the engine off). Before testing or servicing any fuel system hose, fitting, or line, the fuel system pressure must be released. Failure to follow these instructions can result in possible serious or fatal injury.

1. Disconnect both batteries.
2. Using a voltmeter, measure the voltage of each battery.

Is the voltage of each battery greater than 11.5 volts?

Yes

- Go to 3

No

- Troubleshoot and repair low voltage condition.
- Perform the ECM VERIFICATION TEST. Powertrain Verification Test

3. SETUP TO CHECK FUEL TANK MODULE (LIFT PUMP) FLOW

WARNING: The fuel system is under a constant pressure (even with the engine off). Before testing or servicing any fuel system hose, fitting, or line, the fuel system pressure must be released. Failure to follow these instructions can result in possible serious or fatal injury.

1. Reconnect both batteries.

Is special tool #8978 Gas AND Diesel Fuel/Pressure Decay Tester available?

Yes

- Go to 4

No

- Go to 9

4. INSTALL APPROPRIATE FUEL LINE ADAPTER / FITTING FROM SPECIAL TOOL #8978

WARNING: The fuel system is under a constant pressure (even with the engine off). Before testing or servicing any fuel system hose, fitting, or line, the fuel system pressure must be released. Failure to follow these instructions can result in possible serious or fatal injury.

1. Perform the following to purge air from the system:
- With the scan tool, actuate the fuel tank module (lift pump).
- 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 fuel tank module (lift pump).
- 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. For 5.9L engine, the flow rate is 520 ml in 10 seconds. For 6.7L engine, the flow rate is 500 ml in 10 seconds.

Does the average flow rate meet or exceed the specification?

Yes - 5.9L Engine

- Trace source of debris found in screened banjo bolt AND repair as necessary in accordance with Service info. Recheck fuel tank module (lift pump) flow.
- Perform the ECM VERIFICATION TEST. Powertrain Verification Test

Yes - 6.7L Engine

- Test complete.
- Perform the ECM VERIFICATION TEST. Powertrain Verification Test

No

- Remove fuel tank AND fuel tank module in accordance with Service info. Inspect for damage AND debris in AND around fuel tank module. If damaged, replace tank/module as necessary in accordance with Service info. Recheck lift pump flow. If no damage found, replace fuel tank module in accordance with Service info. Recheck lift pump flow.
- Perform the ECM VERIFICATION TEST. Powertrain Verification Test

9. CHECK FUEL TANK MODULE (LIFT PUMP) FLOW

WARNING: The fuel system is under a constant pressure (even with the engine off). Before testing or servicing any fuel system hose, fitting, or line, the fuel system pressure must be released. Failure to follow these instructions can result in possible serious or fatal injury.

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. For 5.9L engine, remove the banjo bolt that attaches the low pressure fuel supply line to the fuel injection pump. Install fuel system test fitting 9014. Then, connect one end of a section of fuel hose to the test fitting and place the other end of the fuel hose into an empty fuel container.
2. For 6.7L engine, disconnect the low pressure fuel supply line from the fuel injection pump. Install fuel system test fitting 9863 onto the end of the low pressure fuel supply line. Then, connect one end of a section of fuel hose to the test fitting and place the other end of the fuel hose into an empty fuel container.
3. Turn the ignition on.
4. With the scan tool, actuate the fuel tank module (lift pump).
5. With the lift pump running, place the fuel hose into a 1000 ml graduated cylinder for 10 seconds and then return the hose to the fuel container.

CAUTION: Stop all actuations.

6. Turn the ignition off.
7. Measure the amount of fuel in the graduated cylinder. For 5.9L engine, the fuel output specification is 590 ml in 10 seconds. For 6.7L engine, the fuel output specification is 570 ml in 10 seconds.

Does the amount of fuel in the graduated cylinder meet or exceed the specification?

Yes

- Test complete.
- Perform the ECM VERIFICATION TEST. Powertrain Verification Test

No - 5.9L Engine

- Leave the tools installed. Go to 10

No - 6.7L Engine

- Leave the tools installed. Replace the fuel filter/water separator. During filter replacement, be sure to check and clean the secondary filter screen. Go to 11

10. CHECK FOR DEBRIS IN SCREENED BANJO BOLT - 5.9L ENGINE

WARNING: The fuel system is under a constant pressure (even with the engine off). Before testing or servicing any fuel system hose, fitting, or line, the fuel system pressure must be released. Failure to follow these instructions can result in possible serious or fatal injury.

1. Remove the screened banjo bolt from the fuel filter outlet and verify that it is free of debris. If debris is found, rinse the screen with water and then blow dry.

Was debris found in the screen?

Yes

- Reinstall the banjo bolt. Go to 11

No

- Replace the fuel filter/water separator. Go to 11

11. RECHECK FUEL TANK MODULE (LIFT PUMP) FLOW

WARNING: The fuel system is under a constant pressure (even with the engine off). Before testing or servicing any fuel system hose, fitting, or line, the fuel system pressure must be released. Failure to follow these instructions can result in possible serious or fatal injury.

1. Turn the ignition on.
2. With the scan tool, actuate the fuel tank module (lift pump).
3. With the lift pump running, place the fuel hose into a 1000 ml graduated cylinder for 10 seconds and then return the hose to the fuel container.

CAUTION: Stop all actuations.

4. Turn the ignition off.
5. Measure the amount of fuel in the graduated cylinder. For 5.9L engine, the fuel output specification is 590 ml in 10 seconds. For 6.7L engine, the fuel output specification is 570 ml in 10 seconds.

Does the amount of fuel in the graduated cylinder meet or exceed the specification?

Yes - 5.9L Engine

- Trace source of debris found in screened banjo bolt and repair as necessary in accordance with Service info. Recheck fuel tank module (lift pump) flow.
- Perform the ECM VERIFICATION TEST. Powertrain Verification Test

Yes - 6.7L Engine

- Test complete.
- Perform the ECM VERIFICATION TEST. Powertrain Verification Test

No

- Remove fuel tank AND fuel tank module in accordance with Service info. Inspect for damage AND debris in AND around fuel tank module. If damaged, replace tank/module as necessary in accordance with Service info. Recheck lift pump flow. If no damage found, replace fuel tank module in accordance with Service info. Recheck lift pump flow.
- Perform the ECM VERIFICATION TEST. Powertrain Verification Test