Fuel Pump Return Flow Test
FUEL PUMP RETURN FLOW TESTPOSSIBLE CAUSES
- Excessive fuel pump return flow
Diagnostic Test
1. FUEL PUMP RETURN FLOW TEST
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.
Remove the banjo bolt from the pressure-limiting valve on the fuel rail.
Install fuel system test fitting #9013 into the pressure-limiting valve.
Attach one end of a fuel hose to the fuel fitting and put the other end of the fuel hose into a container
Perform the tests listed below to determine if the pressure-limiting valve is leaking.
a. Operate the engine at idle and watch for fuel flow into the fuel container.
b. 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.
If fuel flows into the fuel container, replace the pressure-limiting valve. If fuel does not leak from the pressure-limiting valve, the test is complete.
NOTE: do not drive the vehicle with any portion of this test kit installed
Operate the engine until the engine is at operating temperature.
Remove the banjo connector from the fuel drain tube at the rear of the fuel filter housing
Install fuel system test fitting #9012 in place of the banjo connector.
Install a piece of fuel line onto the test fitting and put the open end into the graduated cylinder.
Start the engine and let it idle for one minute.
Measure the amount of fuel in the graduated cylinder.
If the flow is less than 1000-ml/minute at idle, the test has successfully passed.
If the flow is greater than 1000 ml/minute at idle, replace the fuel injection pump.
Retest to confirm repair.
View Repair
Repair
Test Complete.
Perform the POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). Powertrain Verification Test - Ver 1