Fuel Pump Return Flow Test

FUEL PUMP RETURN FLOW TEST






1. CHECKING THE PRESSURE LIMITING VALVE PRESSURE LIMITING VALVE RETURN FLOW

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

1. Using the scan tool, idle the engine and measure the rail pressure and determine if the rail pressure is excessive (above 185,00 kpa/26,831 psi). If it is, troubleshoot for excessive rail pressure first.
2. Remove the banjo bolt from the Pressure-Limiting Valve on the fuel rail.
3. On a 6.7L install fuel system test fitting 9013 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.
5. Perform the tests listed below to determine if the Pressure-Limiting Valve is leaking.
6. Operate the engine at idle and watch for fuel flow into the fuel container.
7. Operate the engine at idle and actuate the high pressure safety valve test with the scan tool. Watch for fuel flow into the fuel container.

Is fuel flowing into the container?

Yes

- Replace the Pressure-Limiting Valve.
- Perform the ECM VERIFICATION TEST. Powertrain Verification Test.

No

- Go To 2

2. FUEL PUMP RETURN FLOW TEST
1. Run the engine until operating temperature is reached.
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.
5. Install a piece of fuel line onto the test fitting and put the open end into the graduated cylinder.
6. Start the engine and let it idle for one minute.
7. Measure the amount of fuel in the graduated cylinder.
8. The fuel flow should be less than 1000ml/minute at idle.

Is the flow less than 1000ml/minute at idle?

Yes

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

No

- Replace the Fuel Injection Pump.
- Perform the ECM VERIFICATION TEST. Powertrain Verification Test.