Deck 7: Fuel System and Related Input Sensorsoutput Actuators Diagnosis

Question 1

What does the term injection pulse width refer to?

A) the off time of the fuel injector
B) the on time of the fuel injector
C) the voltage required to turn on the fuel injector
D) none of the above

Answer 1

B

Question 2

Low supply voltage at the fuel pump may result in low fuel pump volume.

Answer 2

True

Question 3

An injector balance will identify a restricted fuel injector.

Answer 3

True

Question 4

A stethoscope may be used to find a malfunctioning fuel injector.

Question 5

Technician A says that the fuel system volume test can help to identify a restricted fuel filter. Technician B says that the fuel system pressure test is one of the first tests that should be performed during fuel system diagnosis. Who is correct?

A) A only
B) B only
C) both A and B
D) neither A nor B

Question 6

Technician A says that disconnecting the vehicle battery during diagnosis may erase the adaptive strategy from the PCM. Technician B says that a vacuum leak may be misdiagnosed as a fuel delivery problem. Who is correct?

A) A only
B) B only
C) both A and B
D) neither A nor B

Question 7

On OBD II systems, failure to clear DTCs will result in the temporary disablement of the non-continuous system monitors.

Question 8

During engine operation, the crankshaft position sensor (CKP) identifies crankshaft position, engine speed, and:

A) direction of crankshaft rotation
B) fluctuations in engine revolutions
C) fluctuations in engine revolutions
D) camshaft speed

Question 9

A vacuum leak may cause the engine idle speed to be lower than specified.

Question 10

A rich air/fuel ratio may be caused by low fuel pump pressure.

Question 11

The term injection pulse width refers to:

A) the off time of the fuel injector
B) the on time of the fuel injector
C) the voltage required to turn on the fuel injector
D) none of the above

Question 12

The minimum idle speed adjustment procedure is the same for all years and makes of the vehicles.

Question 13

If the RPM signal is lost on an electronic fuel-injected vehicle, which of the following conditions will exist?

A) The ignition timing will be set to zero.
B) The PCM will go into backup mode base settings.
C) The engine will not run.
D) The vehicle will hesitate.

Question 14

A higher than normal idle speed may be caused by low system voltage.

Question 15

Disconnecting the vehicle battery during diagnosis may deprogram the radio.

Question 16

Technician A says that an air leak between the MAF sensor and the throttle plate will cause the MAF sensor to indicate to the PCM that less air is entering the engine in relation to the throttle opening. Technician B says that an air leak between the MAF sensor and the throttle plate is considered an uncalibrated air leak. Who is correct?

A) A only
B) B only
C) both A and B
D) neither A nor B

Question 17

A vehicle is brought in for a complaint of a rotten egg smell coming from the exhaust. The most likely cause is:

A) engine misfire
B) rich fuel command
C) both A and B
D) neither A nor B

Question 18

Engine surging at idle may be caused by dirty fuel injectors.

Question 19

The quantity or volume of fuel delivered to the cylinders by the fuel injectors is determined by:

A) the fuel pressure regulator
B) the length of time that the PCM supplies a ground signal to the injectors
C) the fuel pressure temperature sensor
D) the length of time that the PCM supplies a power signal to the MAF sensor

Question 20

How should the PCM react if the oxygen sensor detects a low oxygen level in the exhaust stream?

A) decrease fuel delivery
B) increase fuel delivery
C) open the EGR valve
D) open the EVAP canister purge solenoid

Question 21

What is the first step that must be performed after attaching a fuel pressure gauge to a fuel system?

Question 22

What is the most likely cause of a customer complaint of a rotten egg odor?

Question 23

What is the purpose of the inertia switch in the fuel pump circuit?

Question 24

On a multiport fuel-injected vehicle, what could cause fuel pressure to remain constant when the throttle is opened rapidly?

Question 25

Why have many manufacturers integrated a returnless fuel system into their fuel system designs?

Question 26

How does the PCM control the air/fuel ratio on fuel-injected engines?

Question 27

How are SFI injectors controlled by the PCM?

Question 28

How does the PCM task manager affect fuel delivery?

Question 29

What effect could a plugged fuel system return line have on the fuel delivery system?

Question 30

How does the fuel system monitor treat one-trip and two-trip faults detected in the fuel delivery system?

Question 31

On a return-style fuel injection system, what could cause high fuel pressure, and what would the results be?

Question 32

What is the primary function of the fuel control system?

Question 33

Increasing injector pulse width has what effect on the air/fuel ratio?

Question 34

What could cause a fuel-injected engine to run on (diesel) after the vehicle is turned off?

Question 35

What is one reason for the requirement of high system fuel pressures in port fuel-injected vehicles?

Question 36

Why are OBD II vehicles equipped with a fuel system monitor?

Question 37

What would the engine operational problem be on a vehicle with a defective fuel pump relay if the vehicle has an oil pressure switch wired in parallel to the fuel pump relay?

Question 38

What are four components that are supplied voltage by the ASD relay on some vehicles?

Question 39

If a vehicle is not equipped with a mass air flow (MAF) sensor, how does the PCM determine the volume of the incoming air charge drawn into the combustion chamber?

Question 40

The PCM makes what assumption regarding the availability of fuel at the injectors?