Deck 7: Fuel Subsystems

Question 1

What shop tools can be used to test inlet restriction on primary fuel filters?

A) Negative pressure gauge or manometer.
B) Fuel system scan tool.
C) Master pyrometer.
D) Positive pressure gauge.

Answer 1

A

Question 2

What is the main reason most recently manufactured vehicles use sealed fuel subsystems?

A) Sealed systems provide better fuel economy.
B) To meet current emission standards.
C) Limit the ingestion of fuel contaminants.
D) Sealed systems are more reliable and less expensive to manufacture.

Answer 2

C

Question 3

What are two types of plunger pumps are used in fuel subsystems?

A) Electrical a hydraulic.
B) Single acting and double-acting.
C) Single plunger and double plunger.
D) Cam driven and solenoid.

Answer 3

B

Question 4

How do most manufacturers prefer technicians prime secondary fuel filters?

A) After installation using the priming pump.
B) After installation by hand.
C) Before the primary filter.
D) Pre-charged before installation.

Question 5

What shop items can be employed to test for water in fuel (WIF)

A) Hydrometer.
B) Water detection meter.
C) Water-detection paste and aluminum welding rod.
D) Digital multi-meter (DMM).

Question 6

Which type of fuel systems are most sensitive to dirt intrusion?

A) Hydraulic
B) Vented.
C) Self priming.
D) Common rail (CR)

Question 7

What fuel system component usually charges the secondary fuel filter?

A) Primary filter.
B) High pressure injection circuit.
C) Fuel pump solenoid.
D) Transfer pump.

Question 8

What function does the fuel sub-system charging circuit perform?

A) Supplies the injectors with high pressure fuel.
B) Supplies ambient pressure fuel to the injectors.
C) Converts low pressure fuel to injection pressure fuel.
D) Supplies the high pressure injection circuit with filtered fuel.

Question 9

What are the four categories of fuel transfer pumps used on diesel engines?

A) Plunger, gear, vane and diaphragm.
B) Plunger, flutter, vane and diaphragm.
C) Centrifugal, centripetal, suction and pressure.
D) Electric, hydraulic, mechanical and electromechanical.

Question 10

What is the fuel return circuit also known as?

A) Pressure relief circuit.
B) Dump circuit.
C) Recirculation circuit.
D) Leak-off circuit.

Question 11

In what forms does water appear in diesel fuel?

A) Ice crystals, droplets and puddles.
B) Only in a semi-absorbed state.
C) Solid, liquid and vapor.
D) Free state, emulsified and semi-absorbed.

Question 12

Technician A states fuel tank sending units can be tested installed using a scan tool. Technician B states sending units can be tested removed using a DMM to test sending unit resistance.

A) Technician A only.
B) Technician B only.
C) Both A and B.
D) Neither A nor B.

Question 13

What component is used on many current systems to continually hold the injectors under a moderate fuel charge?

A) Fuel pump.
B) Injector low pressure connectors.
C) Fuel rail.
D) Pressure regulator.

Question 14

What two designs of fuel pre-heaters are currently in use?

A) Compression and electric.
B) Pressurized and non-pressurized.
C) Electric and engine coolant.
D) Exhaust and electric.

Question 15

Why do fuel systems circulate more fuel than required to fuel the engine?

A) Fuel is also used for lubrication and cooling.
B) To continually re-filter the fuel.
C) To help maintain the fuel at a proper temperature.
D) As a fail safe to prevent fuel starvation.

Question 16

Technician A states the fuel subsystem must supply clean fuel to the injection circuit by filtering out impurities and particulates. Technician B states that fuel subsystems circulate fuel to help cool engine components. Which technician is correct?

A) Technician A only.
B) Technician B only.
C) Both A and B.
D) Neither A nor B.

Question 17

What condition is indicated by blown off tips on fuel injectors?

A) Engine overheating.
B) Water contamination in fuel.
C) Engine backfires caused by poorly adjusted timing.
D) Pre-detonation.

Question 18

How is fuel filter efficiency rated?

A) Maximum flow rate.
B) Entrapment capability in microns
C) Service life expectations.
D) Maximum pressure rating in psi.

Question 19

What two circuits can most fuel subsystems be divided into?

A) Primary and secondary circuits.
B) Filtered circuit and non-filtered circuit.
C) Fuel and lubrication circuits.
D) High pressure and low pressure circuit.

Question 20

What method of aspirating fuel subsystems is currently favored by manufacturers?

A) Fully-vented fuel subsystems.
B) Sealed fuel subsystems.
C) High pressure fuel subsystems
D) Combination vented/sealed fuel subsystems.