Fuel System - Fuel Quality Testing
Group: FUEL SYSTEMNumber: 10-FL-013
Date: NOVEMBER 2010
Subject
TESTING FUEL QUALITY TO DIAGNOSE ENGINE
STARTABILITY / HESITATION / DRIVEABILITY ISSUES
DESCRIPTION:
This bulletin outlines the basic components of the BG Fuel Test Kit and the procedure to test the quality of the fuel during vehicle diagnosis.
Poor fuel quality may lead to cold engine startability issues, hesitation at idle or during acceleration, and/or poor driveability. In addition, prolonged vehicle operation with poor quality fuel may result in damage to the fuel system and formation of engine deposits.
The BG Fuel Test Kit can be used to determine the following aspects of the fuel:
^ Sediment / Water Contamination Inspection
^ Specific Gravity
^ Alcohol Content
APPLICABLE VEHICLES:
^ ALL MODELS equipped with gasoline engines
PARTS INFORMATION:
The BG Fuel Test Kit (P/N J-48983) is the approved fuel quality testing tool to be used during vehicle diagnosis. This kit is an essential tool that has been sent to all dealers and is part of the new dealer kit.
Contents of the kit:
- Hydrometers (gasoline / diesel)
- Graduated cylinder (100ml)
- Graduated cylinder (alcohol test)
- Graduated cylinder small stopper
- Graduated cylinder holding fixtures
- Specific gravity vs. temperature reference chart. (shown below / right)
IMPORTANT:
The kit includes TWO (2) different hydrometers.
Do not use the diesel hydrometer with specific gravity range from 0.800 to 0.900.
Use only the gasoline hydrometer with specific gravity range from 0.700 to 0.800 for the correct measurement of the fuel to be tested.
SERVICE PROCEDURE:
1. Prepare the tall graduated cylinder attached to the fixture base.
NOTE:
Be sure that the inside of the cylinder is clean and free of contaminants.
2. Obtain sample fuel from the incident vehicle and fill the graduated cylinder to the 100ml mark.
NOTE:
There are several different methods available to gather a small quantity of fuel for testing. Follow the applicable Shop Manual procedures and precautions as required to perform any ONE of the following, as feasible.
^ For older MPI fuel systems equipped with a fuel return line, divert the fuel return hose to capture the fuel into a suitable container while running the engine at idle.
^ For MPI fuel systems that are returnless design, divert the fuel line from the fuel rail to capture the fuel into a container. For additional fuel amount, briefly prime the fuel pump by cycling the ignition key. (Do not perform this option for GDI engines.)
^ For GDI and MPI systems, lift the vehicle and disconnect the large fuel hose of the fuel filler neck from the fuel tank inlet. Using a long socket extension, lightly push open the inlet check valve at the inlet of the tank and capture the sample fuel.
^ For GDI and MPI systems, remove the main fuel pump and sender module from the fuel tank to collect the fuel sample through the service access port, if possible. If equipped, removing the remote fuel sender module may be easier for this task. Avoid fuel spillage.
3. Visually inspect the collected fuel sample for presence of sediment, debris, or water contamination. (Example shown at right. Replace fuel if contamination is found.)
4. Insert the thermometer into the graduated cylinder and attach the clip to the top rim.
5. Wait a few minutes to allow for the temperature to stabilize, then record the measured temperature of the gasoline sample. Remove the thermometer afterwards.
6. Insert the gasoline hydrometer with specific gravity range from 0.700 to 0.800 into the graduated cylinder and wait until it stabilizes while floating in the fuel.
7. Read the number at the liquid line on the side of the hydrometer.
8. Refer to the supplied reference chart to look up the measured temperature and the hydrometer reading to find the corresponding specific gravity. (Examples shown)
NOTE:
The fuel tanks of vehicles having contaminated fuel or fuel outside the NORMAL specific gravity range should be drained and refilled.
9. Prepare the small graduated cylinder for fuel alcohol content testing.
NOTE:
Be sure that the inside of the cylinder is clean and free of contaminants.
10. With the stopper cap removed, add clean water up to the (A) water fill line.
11. Add fuel from the tall graduated cylinder to the (B) fuel fill line.
12. Insert the stopper cap at the top to seal it and vigorously shake the contents for at least 10 seconds or more.
13. Let the mixture settle for approximately 5~10 minutes.
NOTE:
At this point, any alcohol of the sample will combine with water and begin to separate from the fuel.
14. Read the line where it separates and find the corresponding (D) alcohol % level of the fuel sample.
NOTE:
High alcohol content in the fuel can cause lean codes and other engine startability and driveability conditions.
15. After completing the fuel tests, prepare the Fuel Test Kit for storage.
^ Rinse all pieces with window cleaner and water, then towel dry thoroughly.
^ Store the reference chart behind the protection foam.
^ Arrange all the components so that they are protected by the clamshell storage case.
WARRANTY INFORMATION:
When necessary, the use of the BG Fuel Test Kit as a part of the normal diagnostic troubleshooting process may be covered under warranty.
However, if the root cause of the condition results from poor fuel quality, then some or all parts and labor expenses may not be covered under warranty.