Deck 31: Amplified Common Rail Systems

Question 1

Which of the following is another way of describing the ACRS fuel system?

A) APTR
B) FACR
C) LPCR
D) CRAS

Answer 1

FACR

Question 2

Technician A says that in a diesel ACRS fuel system, the rail supplies all of the injectors required to fuel the engine. Technician B says that the rail pressures in a diesel ACRS fuel system are designed to be widely variable. Who is correct?

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

Answer 2

Both A and B

Question 3

Which of the following acronyms is the odd one out?

A) FACR
B) ACRS
C) APCR
D) CR

Answer 3

CR

Question 4

What component is used to control the rail pressure of an ACRS diesel fuel system in any given moment of operation?

A) rail pressure sensor (RPS)
B) quantity control valve (QCV)
C) EHI solenoid
D) rail pressure regulator (RPR)

Question 5

Technician A says that desired rail pressure in a ACRS fuel system is signaled by the QCV. Technician B says that actual rail pressure in an ACRS fuel system is calculated by the ECM. Who is correct?

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

Question 6

What type of injector is used in a Detroit Diesel ACRS system?

A) Hydraulically-amplified diesel injector (HADI)
B) Poppet injectors
C) Multi-orifice injectors
D) electrohydraulic injectors (EHIs)

Question 7

On which engine was the ACRS fuel system introduced in North America in 2008?

A) Cummins ISX
B) Detroit Diesel DD15
C) Paccar MX-385
D) Detriot Diesel DD13

Question 8

Which of the following serves a role as an accumulator in an ACRS fuel system?

A) Hydraulic head
B) Rail
C) Pump chamber
D) Amplifier chamber

Question 9

Technician A says that the when a HADI is operated in non-amplification mode, the resulting injection pressure should be roughly equivalent to the ACRS rail pressure. Technician B says that when the HADI is operated in amplification mode, ACRS injection pressure can more than double the rail pressure. Who is correct?

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

Question 10

What is used to switch a quantity control valve used in a typical ACRS fuel system?

A) Pulse width modulated signal
B) Analog voltage charge
C) Fuel volume in accumulator
D) Hydraulic distributor head

Question 11

Which of the following best describes the type of pump used with the DD-Series ACRS fuel system?

A) Rotary distributor
B) Inline piston
C) Radial piston
D) Opposed plunger

Question 12

How many pistons are used in the DD-Series ACRS piston pump?

A) One
B) Two
C) Three
D) Six

Question 13

Technician A says that a disadvantage of a HADI over a standard EHI, is that the HADI nozzle seat has to seal much higher rail pressures. Technician B says that the high pressure piston pump used with the current DD-Series ACRS is supplied by Bosch. Who is correct?

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

Question 14

How does the DD-Series ACRS quantity control valve (QCV) manage rail pressure?

A) By optioning high pressure fuel back to the tank directly from the rail
B) By siphoning fuel from the HADIs
C) By limiting fuel admitted to the transfer pump inlet
D) By controlling fuel admitted to the high pressure pump elements

Question 15

Technician A says that ACRS pressure during injection should be roughly equivalent to the rail pressure in all modes of operation. Technician B says that HADI injection pressure is managed by the motor control module (MCM). Who is correct?

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

Question 16

Technician A says that the DDEC 10 is used to manage post-2010 DD-Series engines with ACRS fuel systems. Technician B says that DDEC VI was used to manage the first generation of DD-Series engines. Who is correct?

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

Question 17

What is used to lubricate the high pressure piston pump used on the DD-Series ACRS fuel system?

A) Fuel
B) Isolated oil supply
C) Engine lubrication circuit
D) Lubriplate

Question 18

What is another way of describing the HADI injector quantity compensation code (IQCC)?

A) rail pressure
B) fuel flow code to balance injectors
C) peak injection pressure rating
D) leak-off pressure differential

Question 19

Technician A says that an ACRS peak injection pressures can exceed 30,000 psi (1,034 bar)in non-amplification mode. Technician B says that the DD3 engine is also supplied to Mitsubishi Fuso trucks. ACRS fuel delivery timing is limited by cam profile. Who is correct?

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

Question 20

Technician A says that the IQCC for each DD-Series HADI must be reprogrammed to the MCM every time an injector is changed out. Technician B says that failure to reprogram a HADI IQCC on change-out can result in unbalanced engine fueling. Who is correct?

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

Question 21

What do DDC recommend when determining whether the rail to HADI high pressure pipes can be re-used?

A) They should never be re-used
B) Re-use permitted but must be monitored carefully after re-torque
C) When one fails, the other five should be changed.
D) They should last the life of the engine

Question 22

How many digits are there in an IQCC code?

A) two
B) four
C) six
D) eight

Question 23

Technician A says that desired rail pressure in a DD-Series ACRS fuel system is calculated by the MCM. Technician B says that actual rail pressure in a DD-Series ACRS fuel system is signaled to the MCM by the rail pressure sensor. Who is correct?

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

Question 24

Which of the following ratios represents the approximate amplification ratio used on the DDC DD-Series ACRS engines?

A) 2:1
B) 3:1
C) 4:1
D) 7:1

Question 25

Technician A says that the ACRS fuel system allows lower rail pressures to generate higher injection pressures. Technician B says that the ACRS fuel system reduces the tendency of EHIs to leak externally because the seat is not exposed to rail pressure when the injector is closed. Who is correct?

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