Gasoline Fuel Systems

25 Questions | Total Attempts: 1234

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Gasoline Fuel Systems

Chapter 48


Questions and Answers
  • 1. 
    The most important job of the fuel system is to optimize engine performance while:
    • A. 

      Keeping fuel consumption and emissions to a minimum.

    • B. 

      Keeping car owners happy with acceptable vehicle performance.

    • C. 

      Making sure all DMV rules are adhered to.

    • D. 

      Making sure all DMV rules are adhered to.

  • 2. 
    Early mechanically operated fuel systems typically sprayed:
    • A. 

      Fuel from an injector in the throttle body on the intake manifold.

    • B. 

      A pulsed stream of fuel delivered behind the intake valves.

    • C. 

      A sequential delivery of fuel from individual injectors on the intake manifold.

    • D. 

      A continuous flow of fuel through injectors at each intake port.

  • 3. 
    All of these are advantages of electronically controlled fuel injection over mechanical injection systems EXCEPT:
    • A. 

      Continuous air–fuel adjustments are possible.

    • B. 

      Reduced emissions are achieved.

    • C. 

      Fuel can be delivered in a continuous stream.

    • D. 

      Reduced fuel consumption is achieved.

  • 4. 
    Tech A says that an electronic control unit (ECU)/power train control module (PCM) is needed to make electronic fuel injection (EFI) function correctly. Tech B says that most early EFI systems were throttle body injection (TBI) type systems. Who is correct?
    • A. 

      Tech A

    • B. 

      Tech B

    • C. 

      Both Techs A and B

    • D. 

      Neither Tech A nor B

  • 5. 
    All of these are subsystems of modern fuel injection systems EXCEPT:
    • A. 

      A fuel supply system.

    • B. 

      An emissions system.

    • C. 

      An air supply system.

    • D. 

      A fuel metering system.

  • 6. 
    Which of these fuel characteristics helps to prevent the air–fuel mixture from spontaneously igniting in the combustion chamber?
    • A. 

      The ignition temperature

    • B. 

      The octane rating

    • C. 

      The cetane rating

    • D. 

      The antiknock rating

  • 7. 
    For gasoline to burn properly, it must be mixed with the right amount of:
    • A. 

      Carbon.

    • B. 

      Air.

    • C. 

      Hydrogen.

    • D. 

      Lead.

  • 8. 
    Which of these describes when the air–fuel mixture spontaneously ignites before the spark plug fires?
    • A. 

      Detonation

    • B. 

      Advanced ignition

    • C. 

      Spark advance

    • D. 

      Pre-ignition

  • 9. 
    Tech A says that a slightly lean mixture offers good fuel economy and low exhaust emissions. Tech B says that a mixture that is too rich fouls spark plugs and causes incomplete burning. Who is correct?
    • A. 

      Tech A

    • B. 

      Tech B

    • C. 

      Both Techs A and B

    • D. 

      Neither Tech A nor B

  • 10. 
    For a gasoline engine, the optimum air to fuel ratio by mass is about: 
    • A. 

      12.1:1.

    • B. 

      14.7:1.

    • C. 

      16.3:1.

    • D. 

      18.5:1.

  • 11. 
    The term “stoichiometric ratio” describes the chemically correct air–fuel ratio necessary to achieve all of these EXCEPT:
    • A. 

      Complete combustion of the fuel and air.

    • B. 

      Good fuel economy.

    • C. 

      Maximum engine power.

    • D. 

      Reasonably clean emissions.

  • 12. 
    Tech A says that most fuel-injected vehicles use one or two electrical pumps to supply the fuel system with pressurized fuel. Tech B says that with today's systems, a fuel pump is likely to be located inside the fuel tank. Who is correct?
    • A. 

      Tech A

    • B. 

      Tech B

    • C. 

      Both Techs A and B

    • D. 

      Neither Tech A nor B

  • 13. 
    A resistor that changes its resistance with changes of temperature is called a:
    • A. 

      Thermistor.

    • B. 

      Transistor.

    • C. 

      Potentiometer.

    • D. 

      Rheostat.

  • 14. 
    Modern fuel filters typically have all of these characteristics EXCEPT:
    • A. 

      They use pleated paper as a filter element.

    • B. 

      They prevent small amounts of water from getting past.

    • C. 

      They serve as an accumulator to quiet the system.

    • D. 

      They are directional in nature.

  • 15. 
    Which of these is a sensor for measuring crankshaft position?
    • A. 

      Camshaft position sensor (CMP)

    • B. 

      Crankshaft position sensor (CKP)

    • C. 

      Intake air temperature (IAT)

    • D. 

      Manifold absolute pressure sensor (MAP)

  • 16. 
    The purpose of the vehicle speed sensor (VSS) is to measure the:
    • A. 

      Turbulence in the incoming airstream.

    • B. 

      Throttle position.

    • C. 

      Speed of the vehicle.

    • D. 

      Coolant temperature.

  • 17. 
    The barometric pressure (BARO) sensor works in conjunction with the:
    • A. 

      Mass airflow (MAF) sensor.

    • B. 

      Manifold absolute pressure (MAP) sensor.

    • C. 

      Vehicle speed sensor (VSS).

    • D. 

      Intake air temperature (IAT) sensor.

  • 18. 
    Which of these has the function of monitoring the noise that is created by a pressure spike in the combustion chamber?
    • A. 

      Barometric pressure (BARO) sensor

    • B. 

      Manifold absolute pressure (MAP) sensor

    • C. 

      Detonation sensor

    • D. 

      Knock sensor

  • 19. 
    Tech A says that engine misfiring will cause a lean exhaust condition. Tech B says that engine misfiring can cause overheating of the catalytic converter. Who is correct?
    • A. 

      Tech A

    • B. 

      Tech B

    • C. 

      Both Techs A and B

    • D. 

      Neither Tech A nor B

  • 20. 
    The on and off time of a stepper motor relates to its duty cycle, which is generally expressed as a:
    • A. 

      Percentage.

    • B. 

      Numeric value.

    • C. 

      Binary number.

    • D. 

      Hexi-decimal value.

  • 21. 
    A variation in pulse width at a fixed frequency is called:
    • A. 

      Duty cycle.

    • B. 

      Analog cycle.

    • C. 

      Pulse-width modulation.

    • D. 

      Digital cycle.

  • 22. 
    Tech A says that fuel pump pressure can often be tested by accessing a test port. Tech B says that fuel pump volume can be affected by the condition of the fuel injectors. Who is correct?
    • A. 

      Tech A

    • B. 

      Tech B

    • C. 

      Both Techs A and B

    • D. 

      Neither Tech A nor B

  • 23. 
    A fuel pump can be tested using a lab scope and a low-amp clamp to:
    • A. 

      Graph the current flow.

    • B. 

      Measure the fuel pressure.

    • C. 

      Measure the volume.

    • D. 

      Test for pressure loss due to leaks.

  • 24. 
    The engine misfire monitor directly detects a fault by monitoring:
    • A. 

      Exhaust emissions.

    • B. 

      Crankshaft rpm.

    • C. 

      Cylinder head temperature.

    • D. 

      Transmission output shaft rpm.

  • 25. 
    The power train control module (PCM) must control a high-current fuel pump. The best actuator to use would be a:
    • A. 

      Bipolar transistor.

    • B. 

      MOSFET.

    • C. 

      Relay.

    • D. 

      Set of drivers.

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