Question 1

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

Accepted Answer

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 
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 2

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?

Accepted Answer

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

Question 3

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

Accepted Answer

A)  fuel sub-system priming 
B)  purging air from cylinder head fuel rail 
C)  purging air from cylinder head oil rail 
D)  pilot injection 
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 4

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

Accepted Answer

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

Question 5

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

Accepted Answer

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

Question 6

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?

Accepted Answer

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

Question 7

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

Accepted Answer

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

Question 8

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

Accepted Answer

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

Question 9

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

Accepted Answer

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

Question 10

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

Accepted Answer

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 
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 11

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

Accepted Answer

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

Question 12

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

Accepted Answer

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

Question 13

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

Accepted Answer

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

Question 14

What event ends the effective pumping stroke of a HEUI?

Accepted Answer

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

Question 15

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?

Accepted Answer

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

Question 16

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

Accepted Answer

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

Question 17

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?

Accepted Answer

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

Question 18

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

Accepted Answer

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

Question 19

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?

Accepted Answer

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

Question 20

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

Accepted Answer

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

Exam 27: Heui Fuel Systems

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

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?

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

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

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

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?

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

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

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

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

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

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

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

What event ends the effective pumping stroke of a HEUI?

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?

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

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?

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

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?

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

Introduction

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Fuel Injection Basics and Governor Principles

Injector Nozzles

Port-Helix Metering Injection Pumps

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Single-Actuator Eui Systems

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