Deck 27: Heui Fuel Systems

Question 1

Which of the following engine OEMs used the HEUI fuel management system up to the EPA 2007 model year?

A) Peterbilt
B) Volvo and Mack Trucks
C) Cummins and Detroit Diesel
D) Caterpillar and Navistar

Answer 1

Caterpillar and Navistar

Question 2

Which of the following engine OEMs uses the HEUI fuel management system on post-2010 highway diesel engines?

A) Caterpillar
B) Navistar
C) Paccar
D) Cummins

Answer 2

Navistar

Question 3

How are fuel injection pressures created within a HEUI injector?

A) hydraulically using fuel as medium
B) hydraulically using engine oil as medium
C) mechanically using a cam profile
D) mechanically using a swash plate pump

Answer 3

hydraulically using engine oil as medium

Question 4

Technician A says that the Caterpillar HEUI system is a full authority, computer controlled engine management system. Technician B says that some HEUI fueled engines are managed hydromechanically. Who is right?

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

Question 5

How is effective pump stroke managed in a HEUI fuel system?

A) engine control module (ECM)
B) mechanical governor
C) throttle position sensor angle
D) road speed governor programming

Question 6

What is commonly used to transfer fuel through the fuel sub-system in most HEUI fueled engines?

A) swash plate type pump
B) vane pump
C) plunger pump
D) centrifugal pump

Question 7

How are HEUIs supplied hydraulically by fuel charging pressure?

A) in series
B) in parallel
C) sequentially by a distributor
D) by an ECM controlled solenoid

Question 8

When a plunger type fuel transfer pump is used with HEUIs, what are typical charging pressure parameters?

A) 30-60 psi
B) 75-110 psi
C) 100-150 psi
D) 150-320 psi

Question 9

Where is the HEUI system hand primer pump usually located on both Caterpillar and Navistar engines?

A) filter pad assembly
B) fuel transfer pump
C) fuel tank
D) fuel rail manifold

Question 10

What is the hydraulic pumping medium used to produce injection pressures in the HEUI fuel management system?

A) hydraulic oil
B) engine coolant
C) fuel
D) engine oil

Question 11

What type of pump is used in the HEUI system to raise the engine oil pressure to actuation pressure values?

A) external gear
B) plunger type
C) swash plate
D) vane

Question 12

HEUI actuation oil pressures fall into which of the following range of values?

A) 30-60 psi
B) 150-300 psi
C) 485 psi - 4000 psi
D) 5000-24,000 psi

Question 13

Technician A says that actuation oil is supplied to the HEUIs in parallel. Technician B says that HEUI actuation oil pressure in managed 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 14

What term does Navistar use to describe what Caterpillar calls an intensifier piston?

A) enhancement
B) amplifier
C) magnifier
D) proportioner

Question 15

Where is the fuel charging pressure regulator located in a Navistar HEUI system?

A) integral with the fuel transfer pump
B) at the exit to the secondary filter
C) at the inlet of the HEUI supply manifold
D) at the exit of the HEUI supply manifold

Question 16

What does an injection pressure regulator (IPR) valve control?

A) length of HEUI effective stroke
B) time of HEUI duty cycle
C) actuation oil pressure
D) fuel injection pressure

Question 17

What controls the linear position of the injection pressure regulator (IPR) in a HEUI fuel system?

A) ECM pulse width modulated signal
B) V-Bat (battery voltage)
C) fuel pressure
D) oil pressure

Question 18

Which of the following best describes the type of injection nozzle used on a HEUI?

A) pintle
B) sac type, multi orifice
C) VCO, multi orifice
D) electrohydraulic

Question 19

When a HEUI is not energized, which of the following is true?

A) actuation oil circulates in the HEUI
B) actuation oil acts only on the intensifier
C) fuel does not enter the HEUI
D) actuation oil cannot enter the HEUI

Question 20

When actuation oil enters the HEUI, which of the following components does it act directly on?

A) nozzle valve
B) fuel pump chamber
C) amplifier piston
D) fuel pressure regulator

Question 21

What is used in the ECM to increase the HEUI solenoid actuation voltage?

A) coil
B) power transistors
C) bridge resistors
D) current modulation

Question 22

What is the actuation voltage typically used to energize HEUI solenoids?

A) 12 volts
B) 50 volts
C) 75 volts
D) 115 volts

Question 23

What is a typical NOP value in a HEUI injector nozzle?

A) 3000 psi
B) Around 5000 psi
C) Around 8,000 psi
D) 24,000 psi

Question 24

By how much does a HEUI amplifier piston exceed the sectional area of the pumping plunger by?

A) one time
B) four times
C) five times
D) seven times

Question 25

If Navistar HEUI actuation oil pressure is specified at 3000 psi at a given moment of operation, what are injection pressures likely to peak at?

A) 3000 psi
B) 9000 psi
C) 12,000 psi
D) 21,000 psi

Question 26

When a HEUI control solenoid is energized, which of the following passages is immediately closed off within the HEUI?

A) PRIME passage
B) pump chamber to nozzle supply duct
C) upper poppet valve seat
D) lower poppet valve seat

Question 27

What is the term Caterpillar use to describe the pilot injection feature of later model HEUIs?

A) IPR
B) IAP
C) ACERT
D) PRIME

Question 28

What event ends the effective pumping stroke of a HEUI?

A) energizing the HEUI solenoid
B) de-energizing the HEUI solenoid
C) injector nozzle closing
D) injector plunger bottoms at BDC

Question 29

When a HEUI solenoid is de-energized, which pressure field collapses first?

A) amplifier piston
B) fuel pumping chamber
C) nozzle pressure chamber
D) actuation oil pressure manifold in head

Question 30

Technician A says that some HEUIs are capable of electronically variable, pilot injection. Technician B says that pilot injection in Caterpillar HEUI injectors is known as PRIME. Who is correct?

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

Question 31

Another way of saying Pre-Injection Metering or PRIME is:

A) fuel sub-system priming
B) purging air from cylinder head fuel rail
C) purging air from cylinder head oil rail
D) pilot injection

Question 32

Technician A says that an advantage of PRIME on a HEUI injector, is that it can be used for cold start conditions and eliminated once the engine is running. Technician B says that PRIME requires the HEUI plunger to have two downstrokes in a single fueling cycle. Who is correct?

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

Question 33

What happens in the HEUI fuel pump chamber when the plunger PRIME recess registers with the pump chamber spill port?

A) chamber recharge
B) plunger retracts
C) pressure collapse
D) end of injection

Question 34

When a HEUI control solenoid is de-energized, what causes the fuel pump plunger to retract?

A) actuation oil pressure collapse
B) fuel pump plunger retraction spring
C) fuel pump chamber pressure
D) all of the above

Question 35

Technician A says that actuation oil pressure always exceeds the fuel injection pressures in a HEUI fuel system. Technician B says that actuation oil pressure in the cylinder head gallery exceeds the fuel charging pressure by a wide margin. Who is correct?

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

Question 36

What determines the emitted droplet sizing from a HEUI?

A) duration ECM is energized
B) plunger descent speed
C) engine rpm
D) length of effective stroke

Question 37

What determines how fast a HEUI amplifier piston is driven through its stroke?

A) actuation oil pressure value
B) duration HEUI control solenoid is energized
C) poppet spill flow area
D) engine rpm

Question 38

When the injector driver power transistor grounds a HEUI control solenoid circuit, what happens?

A) end of HEUI effective stroke
B) engine shutdown
C) beginning of HEUI effective stroke
D) actuation oil spills to rocker housing

Question 39

In what year was the Siemens HEUI introduced on Navistar built engines?

A) 2001
B) 2004
C) 2006
D) 2007

Question 40

Technician A says that the general operating principles of Caterpillar and Siemens built HEUIs are identical. Technician B says that the Siemens HEUI is smaller and lighter than the Caterpillar equivalent. Who is correct?

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

Question 41

What voltage is used to actuate Siemens HEUIs in Navistar applications?

A) 5 volts
B) 12 volts
C) 48 volts
D) 115 volts

Question 42

Technician A says that Siemens HEUI uses a horizontal actuator spool. Technician B says that the HEUI actuator spool linear movement is vertical. Who is correct?

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

Question 43

Technician A says that the Siemens HEUI is equipped with an ON coil and OFF coil arranged on either side of the actuator spool. Technician B says that when the Siemens HEUI ON coil is energized, actuation oil is vented from the HEUI actuation circuit. Who is correct?

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

Question 44

What drives the swash plate pump used in a typical HEUI fuel management system?

A) Dedicate cam profile on camshaft
B) Engine geartrain
C) Rocker-actuated plunger
D) Fuel transfer pump pressure

Question 45

Which company manufacturers HEUI injectors for current (post-2010) Navistar engines?

A) Caterpillar
B) Navistar
C) Bosch
D) Siemens