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CHAPTER 48

CHAPTER 48. Gasoline Fuel Systems. Replacing a Fuel Filter. 48-1.

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CHAPTER 48

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  1. CHAPTER 48 Gasoline Fuel Systems

  2. Replacing a Fuel Filter 48-1 • Refer to the service information to identify the location and type of fuel filter and the correct procedure for removing and replacing it. If the engine is equipped with an electric fuel pump, release the pressure according to the service information.

  3. Replacing a Fuel Filter 48-1 • Obtain the correct replacement filter and components. Loosen the bracket holding the filter in place, if equipped. Follow the steps below according to the type of filter you are replacing. for a flared fitting type of filter:

  4. Replacing a Fuel Filter 48-1 For a flared fitting type of filter: • Disconnect the fuel line on the engine side of the filter using the double wrench method. If necessary, drain any excess fuel into a fuel-proof container.

  5. Replacing a Fuel Filter 48-1 • Disconnect the fuel line on the inlet end of the fuel filter and remove it from the lines.

  6. Replacing a Fuel Filter 48-1 • Reinstall the filter, making sure you have the filter facing in the right direction, with the flow indicator arrow pointing toward the engine. Tighten the fittings on both ends using the double wrench method.

  7. Replacing a Fuel Filter 48-1 For a quick disconnect filter: • Using the correct tool, release the quick disconnect connectors from the outlet end of the filter, catching any leaking fuel in a fuel-proof container.

  8. Replacing a Fuel Filter 48-1 • Release the quick disconnect connectors from the inlet end of the filter, and remove the filter from the lines.

  9. Replacing a Fuel Filter 48-1 • Reinstall the filter, with the flow indicator arrow pointing toward the engine, and fully engage the lines, making sure they are secure.

  10. Replacing a Fuel Filter 48-1 • Wipe any residual fuel off with a clean shop rag, and write the date and mileage on the filter. Remember to replace the fuel pump fuse, if removed.

  11. Replacing a Fuel Filter 48-1 • Turn the key to the on position for 5 seconds, but do not start the engine , and then turn it back to off. Repeat the process two more times, checking the filter connections for leaks. If no leaks are found, start the vehicle, letting it run for 2 to 3 minutes before shutting it off. Recheck the filter connections for leaks.

  12. Inspecting and Testing Fuel Pumps 48-2 • After researching the procedure for testing the fuel pump in the service information, install a fuel pump gauge on the fuel rail test port.

  13. Inspecting and Testing Fuel Pumps 48-2 • Turn the key to the run position and measure the pressure. If none, test the fuel pump's electrical circuit.

  14. Inspecting and Testing Fuel Pumps 48-2 • Start the engine, measure the pressure, and compare to specifications. With the engine running and the end of the fuel line from the fuel pressure gauge in a 1-quart plastic bottle, open the valve on the gauge and stop the fuel flow after 15 seconds.

  15. Inspecting and Testing Fuel Pumps 48-2 • Measure the amount of fuel delivered in that time, and compare to specifications.

  16. Inspecting and Testing Fuel Pumps 48-2 • If the pressure test or volume test was less than specified, you can use a lab scope and low-amps clamp to graph the current flow going to the fuel pump. Remove the fuel pump fuse and connect a jumper lead between the terminals in the fuse box. Place the amps clamp around the jumper lead.

  17. Inspecting and Testing Fuel Pumps 48-2 • Start the engine, look at the lab scope pattern, and compare the pattern to the service information.

  18. Inspecting and Testing Fuel Pumps 48-2 • Record rpm, VSS, front oxygen sensors, short-term fuel trim, and long-term fuel trim under heavy load and at higher rpm. After returning to the shop, look at your recording; if you see a lean oxygen signal with a large increase in fuel trim, the vehicle has a fuel delivery problem.

  19. Checking Fuel for Contaminants and Quality 48-3 • Collect a quantity of fuel from the vehicle's fuel rail in a clear plastic fuel container. Let it settle and check for contaminants, cloudiness, or improper odor.

  20. Checking Fuel for Contaminants and Quality 48-3 • Pour 10 mL of water into the= 100 mL graduated test tube.

  21. Checking Fuel for Contaminants and Quality 48-3 • Add 90 mL of gasoline, bringing the total volume to 100 mL.

  22. Checking Fuel for Contaminants and Quality 48-3 • Cap the test tube tightly. Slowly agitate the fuel–water mixture for 30 seconds. If there is any alcohol in the fuel, this motion will allow the water to be absorbed by the alcohol.

  23. Checking Fuel for Contaminants and Quality 48-3 • Allow the mixture to settle. Observe the level of the water in the bottom of the test tube. Anything higher than the initial 10 mL is the amount of alcohol in the fuel. List your observations and determine any necessary actions.

  24. Checking Fuel for Contaminants and Quality 48-3 • Carefully pour off the fuel in the test tube back into the fuel container. Make sure no water leaves the test tube. Properly dispose of the remaining water–fuel mixture.

  25. Inspecting and Testing Fuel Injectors 48-4 • Measure the resistance of the suspect fuel injector, and compare to specifications. If the resistance is not in specifications, replace the injector.

  26. Inspecting and Testing Fuel Injectors 48-4 • Install the fuel pressure gauge on the fuel rail. Connect the injector pulsing tool to one fuel injector, according to the tool maker's instructions, and set it for the appropriate number and time of pulses.

  27. Inspecting and Testing Fuel Injectors 48-4 • Pressurize the fuel rail by turning on the ignition switch for a few seconds. Then turn the ignition switch off. Record the fuel pressure.

  28. Inspecting and Testing Fuel Injectors 48-4 • Activate the injector pulsing tool for the appropriate amount of time. Watch the pressure gauge and record the pressure after the injector has been pulsed.

  29. Inspecting and Testing Fuel Injectors 48-4 • Repeat this test on each fuel injector, pressurizing the fuel rail each time before activating the injector pulsing tool. Record the pressure readings before and after each test. Compare all readings to specifications and to each other. Determine any necessary actions.

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