Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
2003 Saturn L300FACTORY OEM SERVICE PROCEDURE
Test Procedure
- Turn ON Fuel Composition Tester.
- Verify the Fuel Composition Tester is operational by measuring the AC frequency output with a DVOM. A frequency without a fuel sample in the test cell indicates that the tester is working correctly.
- Install the Gauge Bar Set. See FUEL SYSTEM PRESSURE RELEASE .
- Close the bleed valve on the Gauge Bar Set.
- Place bleed hose (1) of the Gauge Bar Set into 3.4 oz. (100 ml) beaker (2). See Fig 1 .
- Command the fuel pump ON with a scan tool.
- Slowly open the bleed valve on the Gauge Bar Set, until an adequate fuel sample is obtained.
- If water appears in the fuel sample, clean the fuel system and replace the fuel in the vehicle. See FUEL SYSTEM CLEANING under FUEL SYSTEMS in REMOVAL & INSTALLATION - SATURN "L" SERIES article.
- Pour the fuel sample from the beaker (1) into the Fuel Composition Tester (3), until the level of the fuel is at the top of each fuel test port (2). See Fig 2 .
- Observe the diagnostic LEDs on the Fuel Composition Tester. If the Red fuel diagnostic LED is illuminated, a fuel contamination condition exists. See FUEL SYSTEM CLEANING under FUEL SYSTEMS in REMOVAL & INSTALLATION - SATURN "L" SERIES article.
- Measure the output frequency of the Fuel Composition Tester.
- Subtract 50 from the reading on the DVOM to obtain the percentage of alcohol in the fuel sample. See examples in FUEL COMPOSITION TEST EXAMPLES table.
- If the fuel sample contains more than 10 percent ethanol, replace the fuel in the vehicle.
NOTE:
It will be necessary to bleed the Gauge Bar Set a few times in order to obtain an accurate fuel sample.
NOTE:
Do not allow any substances other than gasoline, ethanol/gasoline blends, air, or acetone into the test ports of the Fuel Composition Tester. Contaminants in the Fuel Composition Tester could result in misdiagnosis.
FUEL COMPOSITION TEST EXAMPLES
| Example | Frequency - Hz | Subtract 50 | Ethanol Percent |
|---|---|---|---|
| A | 50 | -50 | 0 |
| B | 65 | -50 | 15 |
| C | 129 | -50 | 79 |
Factory Service Tools
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.