start Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 OBJECTIVES: After studying Chapter 60, the reader should be able to: • • • Prepare for ASE Engine Performance (A8) certification test content area “C” (Fuel, Air Induction, and Exhaust Systems Diagnosis and Repair) Describe how to check an electric fuel pump for proper pressure and volume delivery Explain how to check a fuel-pressure regulator Continued Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 OBJECTIVES: After studying Chapter 60, the reader should be able to: • • • Describe how to test fuel injectors Explain how to diagnose electronic fuel injection problems Describe how to service the fuel injection system Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 KEY TERMS: graphing multimeter (GMM) IAC counts noid light peak-and-hold injector • pressure transducer saturation Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 PORT FUEL-INJECTION PRESSURE REGULATOR DIAGNOSIS Most port­fuel­injected engines use a vacuum hose connected to  the fuel­pressure regulator. At idle, the pressure inside the intake  manifold is low (high vacuum) Manifold vacuum is applied above the diaphragm inside the fuel­ pressure regulator. This reduces the pressure exerted on the  diaphragm and results in a lower, about 10 psi (69 kPa), fuel  pressure applied to the injectors.  Continued Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 To test a vacuum­controlled fuel­pressure regulator: Connect a fuel­pressure gauge to monitor the fuel pressure Locate the fuel­pressure regulator and disconnect the vacuum  hose from the regulator With the engine running at idle speed, reconnect the vacuum  hose to the fuel­pressure regulator while watching the fuel­ pressure gauge. The fuel pressure should drop (about 10 psi  or 69 kPa) when the hose is reattached to the regulator NOTE: If gasoline drips out of the vacuum hose when removed from the fuel­pressure regulator, the regulator is defective and will require replacement Continued Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 Using a hand­operated vacuum pump, apply vacuum (20 in.  Hg) to the regulator. The regulator should hold vacuum. If  the vacuum drops, replace the fuel­pressure regulator NOTE: Some vehicles do not use a  vacuum­regulated fuel­pressure regulator.  Many of these vehicles use a regulator  located inside the fuel tank that supplies a  constant fuel pressure to the fuel injectors Figure 60–1 If the vacuum hose is removed from the fuel-pressure regulator when the engine is running, the fuel pressure should increase If it does not increase, then the fuel pump is not capable of supplying adequate pressure or the fuel-pressure regulator is defective If gasoline is visible in the vacuum hose, the regulator is leaking and should be replaced Continued Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 Pressure Transducer Fuel Pressure Test Using a pressure transducer and a graphing multimeter (GMM) or digital storage oscilloscope (DSO) allows the service tech to view fuel pressure over time, Figure a Note the fuel pressure dropped from 15 to psi on a TBI-equipped vehicle after one minute Normal pressure holding capability is shown in Figure b, when pressure dropped about 10% after 10 minutes (a) (b) Figure 60–2 (a) A fuel-pressure graph after key on, engine off (KOEO) (b) Pressure drop after 10 minutes on a normal port fuel-injection system Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 DIAGNOSING ELECTRONIC FUEL-INJECTION PROBLEMS USING VISUAL INSPECTION All fuel­injection systems require the proper amount of clean fuel  delivered to the system at the proper pressure and the correct  amount of filtered air.  The following items should be carefully inspected before  proceeding to more detailed tests Check the air filter and replace as needed Check the air induction system for obstructions Check the conditions of all vacuum hoses. Replace any hose  that is split, soft (mushy), or brittle Check all fuel­injection electrical connections for corrosion  or damage Continued Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 NOTE: Use of an incorrect PCV valve can cause a rough idle or stalling Figure 60–3 A clogged PCV system caused the engine oil fumes to be drawn into the air cleaner assembly This is what the technician discovered during a visual inspection Check the positive crank­ case ventilation (PCV) valve for proper operation or replacement as needed.  Check for gasoline at the vacuum port of the fuel­pressure  regulator if the vehicle is so equipped. Gasoline in the vacuum  hose at the fuel­pressure regulator indicates that the regulator is  defective and requires replacement Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 Decarbon the engine assembly.  On most vehicles, the  injector spray will help the decarboning process On others, you may need to enhance the operation with  external addition of a mixture through the PCV hose,  throttle plates, or idle air controls Check the Injectors at the “Bends and Ends” Injectors that are most likely to become restricted due to clogging of the filter basket screen are the injectors at the ends of the rail especially on returnless systems where dirt can accumulate Also the injectors that are located at the bends of the fuel rail are also subject to possible clogging due to the dirt being deposited where the fuel makes a turn in the rail Continued Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 Clean the throttle plate and idle air control passages.  Doing this service alone on most late­model engines will show  a manifold vacuum increase of up to 2 in. Hg Clean the areas as needed, then use a handheld fuel injector  connected in parallel with the pressure hose, along with a  pulser to allow cleaning of the throttle plates with the same  chemical as injectors are running on.  This works well as air is drawn into IAC passages on a running engine and will clean the passages without IAC removal Figure 60–28 To thoroughly clean a throttle body, it is sometimes best to remove it from the vehicle Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 Relearn the onboard computer. Some vehicles may have  been running in such a poor state of operation the onboard  computer may need to be relearned. Consult service  information for the suggested relearn procedures This service usually takes approximately one hour for the vehicle  to run out of fuel and the entire service to be performed. The good  thing is that the technician may do other services while this is  being performed Some technicians may install a set of plugs or change the fuel  filter while the engine is flushing. This service should restore the  fuel system to original operations Continued Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 Be Sure To Clean the Fuel Rail Whenever you service the fuel injectors, or if you suspect that there may be a fuelinjector problem, remove the entire fuel rail assembly and check the passages for contamination Always thoroughly clean the rail when replacing fuel injectors Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 See the chart on Page 729 of your textbook.  Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 FUEL SYSTEM SCAN TOOL DIAGNOSTICS Diagnosing a faulty fuel system can be a difficult task that can be  made easier by utilizing the information available via the serial  data stream Observing the long­term fuel trim and the short­term fuel trim can  help determine how the fuel system is performing Short­term fuel trim and long­term fuel trim can help us to zero in  on specific areas of trouble. Readings should be taken at idle and at  3000 rpm Use the chart following Continued Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 See the chart on Page 730 of your textbook.  Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 PHOTO SEQUENCE Fuel Pump Relay Circuit Diagnosis Continued Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 PHOTO SEQUENCE Relay Circuit Diagnosis (cont.) Continued Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 PHOTO SEQUENCE Relay Circuit Diagnosis Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman (cont.) ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 PHOTO SEQUENCE Fuel Injector Cleaning Continued Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 PHOTO SEQUENCE Fuel Injector Cleaning Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman (cont.) ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 SUMMARY A typical throttle­body fuel injector uses a computer­controlled  injector solenoid to spray fuel into the throttle­body unit above  the throttle plates A typical port fuel­injection system uses an individual fuel  injector for each cylinder and squirts fuel directly into the intake  manifold about 3 inches (80 millimeters) from the intake valve A typical fuel­injection system fuel pressure should not drop  more than 20 psi in 20 minutes A noid light can be used to check for the presence of an injector  pulse Continued Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 SUMMARY (cont.) Injectors can be tested for resistance and should be within 0.3 to  0.4 ohms of each other Different designs of injectors have a different scope waveform  depending on how the computer pulses the injector on and off An idle air control unit controls idle speed and can be tested for  proper operation using a scan tool or scope Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 end Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458