Deck 24: Fuel-Injection System Diagnosis and Service

Question 1

Fuel injectors can be tested using ________.

A) a stethoscope
B) an oscilloscope
C) an ohmmeter
D) Any of these

Answer 1

D

Question 2

What should be done if the fuel pressure regulator will NOT hold vacuum?

A) Nothing; this is normal
B) Replacement
C) Adjustment
D) Cleaning

Answer 2

B

Question 3

On a vehicle with a mass airflow injection system, which of the following is likely to occur with a vacuum leak at idle?

A) No fuel mixture change
B) Rich fuel mixture
C) Lean fuel mixture
D) None of these

Answer 3

C

Question 4

Which of these tools is best to check whether the PCM is pulsing an injector?

A) Digital multimeter
B) Analog multimeter
C) Noid light
D) Test light

Question 5

What could be the problem if a noid light remains on (does not flash) with the engine cranking?

A) Short to ground in the injector ground circuit, or defective PCM
B) Low system voltage
C) Blown injector fuse
D) High injector resistance

Question 6

Technician A says that all the fuel injectors on an engine should have the same electrical resistance. Technician B says that the difference between any two injectors should be less than 2 ohms. Which technician is correct?

A) Technician A only
B) Technician B only
C) Both technicians A and B
D) Neither technician A nor B

Question 7

During a fuel injector pressure drop test, the difference between any two fuel injectors should not exceed?

A) 15 PSI
B) 14.7 PSI
C) 1.5 PSI
D) 0.4 PSI

Question 8

Technician A always uses a special service tool to pulse fuel injectors. Technician B says that the injector for each cylinder should only be flow tested four times without starting the engine. Which technician is correct?

A) Technician A only
B) Technician B only
C) Both technicians A and B
D) Neither technician A nor B

Question 9

All of these are types of injector circuits EXCEPT ________.

A) pulse width modulated
B) peak and hold
C) saturated switch
D) All of these are types of injector circuits.

Question 10

When looking at an injector voltage with an oscilloscope, what event often follows removing power from the coil windings?

A) Voltage spike
B) Diode ripple
C) Voltage drop
D) Decreased resistance

Question 11

How much voltage is generally available to fuel injectors?

A) 5 Volts DC
B) 10 Volts DC
C) 7 Volts DC
D) Battery voltage

Question 12

Which term describes the electrical current flow in the opposite direction when an injector coil is energized?

A) Inductive reactance
B) Voltage drop
C) Electromagnetic force
D) Magnetic induction

Question 13

Technician A says that if fuel pump pressure is correct, fuel pump volume will be correct as well. Technician B says that a fuel pump may produce specified pressure but below specified volume. Which technician is correct?

A) Technician A only
B) Technician B only
C) Both technicians A and B
D) Neither technician A nor B

Question 14

An injection cleaning machine is being discussed. Technician A says that the applied pressure should be between 75-90 PSI before starting the engine. Technician B says to pressure clean the fuel system using a 2:1 mixture of solvent to gasoline. Which technician is correct?

A) Technician A only
B) Technician B only
C) Both technicians A and B
D) Neither technician A nor B

Question 15

The following statements are all correct EXCEPT ________.

A) the fuel rail and pressure regulator should be cleaned as well as fuel injectors
B) on engines operating very poorly, the PCM should be relearned after fuel system cleaning
C) fuel systems that have never been cleaned may have developed wax deposits as well as carbon
D) relearning the PCM should never be attempted

Question 16

Which of the following could be a reason for poor cold engine performance?

A) Low fuel pressure
B) Contaminated fuel
C) Insufficient fuel volume
D) All of these are correct

Question 17

Technician A says that a noid light can help when checking the fuel system in a no-start condition. Technician B says that the ignition system trigger device is used to synchronize fuel injection. Which technician is correct?

A) Technician A only
B) Technician B only
C) Both technicians A and B
D) Neither technician A nor B

Question 18

During a fuel pressure test the technician notices that the system does not hold pressure for more than 10 minutes with the engine off. What could be the cause?

A) A bad fuel pressure regulator
B) The fuel filter installed backwards
C) A loose MAF hose
D) A leaking throttle plate