Fuel Contamination
DIESEL FUEL CONTAMINATION TESTING PROCEDURE
OVERVIEW
This procedure explains the proper method for extracting a fuel sample and specific methods to inspect for contamination of any kind. The contamination we are looking for on the clean side of the Fuel Filter is very small. We don't say dirt because it may be metal, water, plastic or any other contamination, other than clean diesel fuel. The smallest we can see with naked eye is about 30 Microns. Our Fuel Filters have 5 Micron rating. The only way we can see this size of contamination is to properly collect it and view it. The fuel sample needs to be taken from the clean side of the system. In order to get a good clean side sample to inspect, perform the following procedure exactly.
1. CLEAN SIDE DIESEL FUEL SAMPLE COLLECTION AND INSPECTION
NOTE: The three photos in this test step illustrate the steps in this test procedure for clarification.
NOTE: The fuel filter MUST NOT be removed or replaced prior to taking sample in order to get accurate results.
NOTE: Warm the engine before collecting the fuel sample.
1. Start the engine and using a scan tool, monitor the Coolant Temperature Sensor reading in Data Display.
2. While the engine is warming up, clean the clear tubing with clean diesel fuel and the glass measuring cup using brake clean and compressed air only. Do not use a towel.
NOTE: Do not use brake clean or other chemicals on any vehicle parts for the fuel handling system such as lines, pumps or fittings.
3. Monitor the scan tool until the vehicle has reached an operating temperature of 180°F (82°C).
4. Turn the engine off.
5. Remove the HPDP return line quick disconnect from the fitting located at the front of the Fuel Filter housing at the banjo bolt joining the Pressure Limiting Valve return (Connection A in the fuel system connections figure above).
NOTE: The fuel flowing from the return of the High Pressure Delivery Pump (HPDP) MUST NOT be part of our sample. We are looking primarily for injector return fuel. The easiest way is to eliminate the HPDP return line and pull the injector return flow sample from the filter mount, on the front side.
6. Cap off the male fitting that the HPDP return line was disconnected from.
7. Disconnect the quick connect fitting for the fuel return line located on the back side of the Fuel Filter housing (Connection B in the fuel system connections figure above).
8. Attach the four foot length of 5/16" clear tubing to this exposed male fitting and orientate it on a downhill angle in to a drain pan. This will be your sample source hose.
9. Using a hose with two male fittings, attach one end to the HPDP return line disconnected in step 5. Connect the other end to the fuel return line disconnected in step 7. This will return the High Pressure Pump return flow back to the tank while collecting the sample.
10. Start the engine, and continue monitoring the coolant temperature to maintain the 180°F (82°C).
11. Using the scan tool, navigate to PCM > System Tests > Fuel Pressure Override Test and select start.
12. Initiate the Fuel Pressure Override Test two consecutive times to further warm the fuel and allow the tubing to be thoroughly rinsed clean.
13. Start the Fuel Pressure Override Test a third time. At mid stream of the test move the clear tube to the measuring cup. Collect a sample of approximately 1/4 inch of fuel in the measuring cup.
14. Turn the engine off.
NOTE: Follow these next steps exactly to inspect the sample for contamination.
15. Allow the sample to sit for 10 minutes in a dust free environment to allow the debris to settle to the bottom. It is important to not allow any air born contaminates to get into the fuel sample. Do not shake, swirl, or agitate the fuel in any way. The contamination should settle to the bottom.
16. Hold the measuring cup (2) by the handle in one hand and shine the LED flashlight (1) through the bottom of the container toward the handle of the cup.
17. Slowly tilt the measuring cup (2) toward you and keep the LED flashlight (1) at the trailing edge of the fuel as it comes down the bottom of the cup and inspect for contamination.
- Any dirt in the fuel will collect and be pulled by this trailing edge of fuel (Number one in the last figure). It may be any color and sometimes looks as though the fuel is cloudy. This is the contamination..
- If you see ANYTHING AT ALL, the fuel is contaminated.
View the following repair options:
The fuel sample is found to be contaminated:
- To ensure that the In Tank Lift Pump is operating properly, perform the Lift Pump Flow Test. For instruction and specifications on this procedure, refer to the CHECKING THE FUEL DELIVERY SYSTEM procedure, test step 5. After checking the In Tank Lift Pump operation, perform the DIESEL FUEL SYSTEM CLEANING PROCEDURE. Cleaning/Reverse Flushing
- Go To 2
The Fuel sample is clean:
- Install new fuel filter and Mopar (CRC) fuel injector cleaner into the fuel tank at a ratio four times the recommend concentration.
- Go To 2
2. DIAGNOSTIC PATH
Were you instructed to inspect for Fuel Contamination from the MIL LIGHT ON PRETEST PROCEDURE?
Yes
- Perform the diagnostic trouble code test that was found to be present. Testing and Inspection.
No
- Go To 3
3. DIAGNOSTIC PATH CONTINUED
Were you instructed to inspect for Fuel Contamination from a Non-DTC TEST PROCEDURE?
Yes
- Perform the DIESEL AFTERTREATMENT VALIDATION 6.7L procedure. Component Tests and General Diagnostics
No
- Return to Diagnostic Test that directed you to inspect for fuel contamination.