Deck 11: Hydraulic Nozzles

Question 1

What is the purpose of a slight amount of fuel leakage around the nozzle valve and into the nozzle spring chamber?

A)To detect a defective nozzle.
B)To lubricate the nozzle valve.
C)To prevent excess fuel delivery.
D)To cool the valve spring and seat.

Answer 1

B

Question 2

When forward leakage from a nozzle is being checked, which of the following is being evaluated?

A)NOP.
B)Nozzle-valve seat sealing.
C)Nozzle valve-to-nozzle body clearance.
D)Injector spring tension.

Answer 2

B

Question 3

Which of the following conditions is caused by a weak nozzle spring?

A)Higher NOP only.
B)Higher NOP and slightly retarded timing.
C)Nozzle chatter.
D)Lower NOP.

Answer 3

D

Question 4

Which of the following emissions would increase the most if a nozzle opening orifice were to become larger because of wear?

A)Carbon monoxide (CO).
B)Particulate matter (PM).
C)Carbon dioxide (CO_2).
D)Oxides of nitrogen (NOx).

Question 5

Technician A says a closed hydraulic nozzle allows combustion gases to mix with fuel inside the nozzle. Technician B says a closed nozzle has no fuel return line back to the fuel tank. Who is correct?

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

Question 6

Technician A says that the nozzles used by DI combustion engines mix air and fuel faster and produce less combustion noise than nozzles used in IDI combustion engines. Technician B says that before the introduction of electronically controlled DI systems, IDI combustion engines produced less noise with fewer emissions and had higher maximum engine rpm than DI combustion engines did. Who is correct?

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

Question 7

Technician A says that nozzle opening pressure (NOP) is adjusted with selective shims placed on top of the nozzle spring. Technician B says that NOP is electronically controlled in some of the latest injectors. Who is correct?

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

Question 8

Technician A says that servo-hydraulic injectors use hydraulically balanced nozzle valves. Technician B says that servo-hydraulic injectors require piezoelectric actuators. Who is correct?

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

Question 9

Technician A says that injection lag takes place when the time between the actual beginning of injection (BOI) lags behind the time when fuel pressurization takes place. Technician B says that injection lag is caused by poor quality fuel with a low cetane number (CN). Who is correct?

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

Question 10

While discussing the purpose of a nozzle lift sensor, Technician A says that the sensor helps calibrate the amount of nozzle lift that an engine's injectors should have. Technician B says the sensor helps produce more precise injection timing. Who is correct?

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

Question 11

When replacing an injector in an engine, Technician A says it is only important to make sure that the replacement injector belongs to the same family or model of engines. Technician B says it is important that for the replacement injector to have a spray pattern that matches the shape of the combustion bowl in the piston. Who is correct?

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

Question 12

Which of the following is the typical nozzle opening pressure (NOP) of a new multi-orifice nozzle?

A)500-5,000 psi (34-345 bar).
B)900-2 500 psi (62-172 bar).
C)2,000-3,200 psi (138-221 bar).
D)3,200-5,500 psi (221-379 bar).

Question 13

Injection delay is caused by _________.

A)fuel with a low cetane number (CN)
B)weak nozzle springs
C)nozzle-valve lift
D)nozzle lift sensors

Question 14

Which type of nozzle is used by a DI combustion chamber?

A)Pintle.
B)Open.
C)Multi-orifice.
D)Pencil.

Question 15

Technician A says that DI combustion chambers use pintle spray nozzles. Technician B says that only multi-orifice nozzles are used in DI combustion engines. Who is correct?

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

Question 16

Technician A says that fewer, smaller spray holes in an injector tip will atomize fuel better than an injector with larger, more numerous holes. Technician B says that fewer, larger spray holes in an injector tip will produce better fuel atomization. Who is correct?

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

Question 17

Which of the following is a likely cause of excessive back leakage from a fuel nozzle?

A)Excessive clearance between the needle valve and nozzle body
B)Excessive spring pressure.
C)Worn nozzle orifices.
D)Needle valve-to-needle seat leakage.

Question 18

The pressure required to open the nozzle valve of an injector, when compared to the pressure required to keep it open, is ______________.

A)much less than closing pressure
B)slightly less than closing pressure
C)equal to closing pressure
D)greater than closing pressure

Question 19

A blocked fuel return line from a nozzle holder could eventually result in which one of the following conditions?

A)A worn-out nozzle holder.
B)Over-fueling the engine.
C)Excessive spray-in pressures.
D)Engine stalling.

Question 20

Technician A says that a driver may be correct when they report that an engine has less power after the injector has been replaced. Technician B says that fuel consumption should decrease after replacing worn-out injectors. Who is correct?

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

Question 21

Hydraulic nozzles are composed of a nozzle valve and nozzle body. Technician A says that the needle valve is the valve in the nozzle that seals the end of the nozzle tip when it is not injecting fuel. Technician B says that there are 4 basic types of nozzles. Who is right?

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

Question 22

Which type of nozzle is used in a direct injection combustion?

A)Pintle"
B)Open"
C)Multi-orifice
D)Pencil"

Question 23

Which of the following is NOT a benefit of finer atomization?

A)Improved mixing of air and fuel for a faster and cleaner burn"
B)Shorter ignition lag time resulting in lower combustion noise"
C)Greater tolerance for use of exhaust gas recirculation (EGR)
D)Lower engine speed because of high-pressure injection systems"

Question 24

What encloses the nozzle assembly and contains a fitting or passageway connecting the high-pressure injection line to the nozzle valve?

A)Mechanical nozzle holder"
B)Hydraulic nozzle holder"
C)Pintle
D)Backleak banjo"

Question 25

What process enhances flow characteristics by removing resistance to fuel flow but also permits, in performance applications, increased fuel delivery?

A)Resistive flow machining"
B)Nitrite process"
C)Abrasive flow machining
D)Haber process"

Question 26

Technician A says that the beginning of injection is the point when fuel delivery begins and is referred to according to the position of the crankshaft measured in degrees of crankshaft rotation. Technician B says to produce the sharp increase in pressure when the nozzle valve first lifts from its seat, it is necessary to ensure that the valve moves very slowly. Who is right?

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

Question 27

Technician A says that injection lag or delay is the time between the start of injection pressurization and the point when fuel is actually being delivered. Technician B says that the needle lift sensor provides an electrical signal to the electronic control module (ECM) that indicates nozzle-valve movement. Who is right?

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

Question 28

What is the purpose of a slight amount of fuel leakage around the nozzle valve and into the nozzle spring chamber?

A)To detect a defective nozzle."
B)To lubricate the nozzle valve."
C)To prevent excess fuel delivery.
D)To cool the valve spring and seat."

Question 29

Which of the following conditions is caused by a weak nozzle spring?

A)Higher NOP only."
B)Higher NOP and slightly retarded timing."
C)Nozzle chatter.
D)Lower NOP."

Question 30

Which of the following emissions would increase the most if a nozzle opening orifice were to become larger because of wear?

A)Carbon monoxide (CO)."
B)Particulate matter (PM)."
C)Carbon dioxide (CO_2).
D)Oxides of nitrogen (NOx)."

Question 31

Technician A says a closed hydraulic nozzle allows combustion gases to mix with fuel inside the nozzle. Technician B says a closed nozzle has no fuel return line back to the fuel tank. Who is correct?

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

Question 32

Technician A says that nozzle opening pressure (NOP) is adjusted with selective shims placed on top of the nozzle spring. Technician B says that NOP is electronically controlled in some of the latest injectors. Who is correct?

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

Question 33

Technician A says that servo-hydraulic injectors use hydraulically balanced nozzle valves. Technician B says that servo-hydraulic injectors require piezoelectric actuators. Who is correct?

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

Question 34

What type of nozzle valve seals the nozzle tip when the valve is seated?

A)Closed injector"
B)Open injector"
C)Controlled injector
D)Limited injector"

Question 35

What type of injector is used in a DI (Direct Injection) diesel engine?

A)Pintle"
B)Multi-orifice"
C)Single-orifice
D)Poppet"

Question 36

Technician A says that DI (Direct Injection) engines require greater capabilities to pressurize, atomize, and distribute fuel than do multi-orifice nozzles. Technician B says that older multi-orifice nozzles use four or five holes, whereas as many 13 can be found in newer designs used in heavy-duty applications. Who is right?

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

Question 37

Most multi-orifice nozzles are calibrated to an NOP (Nominal Opening Pressure) of between:

A)1,300 and 2,500 psi
B)2,300 and 4,500 psi
C)4,300 and 7,500 psi
D)3300 and 5 500 psi"

Question 38

Which of the following increases wear on nozzle valves and seats?

A)Higher pressure"
B)Lower pressure"
C)Poor adjustment
D)Incorrect tightening torque"

Question 39

Which of the following is NOT an effect of using higher NOP (Nominal Opening Pressure)?

A)Low power"
B)Wear on nozzle valve seats"
C)Starting may be more difficult
D)Idling may be less stable"

Question 40

The subject of balanced multi-orifice injectors is being discussed. Technician A says that the Delphi E3 unit injector is an example of a nozzle with electronically controlled variable NOP (Nominal Opening Pressure). Technician B says that some injectors use hydraulically balanced nozzle valves with servo actuators, but can also electronically vary nozzle opening until injection pressures. Who is right?

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

Question 41

What type of nozzle is used only in IDI (Indirect Diesel Injection) combustion chambers?

A)Pintle"
B)Multi-orifice"
C)Single-orifice
D)Poppet"

Question 42

Most pintle nozzles have an average NOP of:

A)500-950 psi"
B)1,000-1,350 psi
C)1,500-1,950 psi
D)2 500-2 950 psi"

Question 43

Technician A says that a pintle nozzle uses a single, large spray hole and is used only in DI (Direct Injection) combustion chambers. Technician B says that fuel spray from a single opening pintle nozzle at low pressure produces poor atomization compared to multi-orifice nozzles. Who is right?

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

Question 44

What serves to mix and vaporize the coarse spray droplets?

A)Turbulent pre-chamber"
B)Mexican hat piston"
C)Valve lip
D)Toroidal Intake passage"

Question 45

Compared to non-electronic DI engines, IDI engines had the advantage of operating at higher speeds with lower air-fuel ratios, noise, and noxious emissions due to the ability of the IDI chamber to rapidly:

A)inject the air and fuel mixture"
B)raise combustion temperature"
C)control RPM
D)prepare the air and fuel mixture"

Question 46

What kind of nozzle, identified by the cone-shaped nozzle body at the injector tip, has an injection rate-shaping feature that reduces the amount of fuel injected during the early stages of injection?
Multi-orifice nozzle

A)Throttle nozzle"
B)Multi-orifice nozzle"
C)Rate shaper nozzle
D)Venturi nozzle"

Question 47

Technician A says that some service facilities do test and repair the hydraulic nozzles used inside injectors because cleaning and rebuilding a nozzle in house is often more economical than replacing it. Technician B says when a problem with an injector is identified by the heavy-duty onboard diagnostics (HD-OBD) system or by using cylinder cutout and contribution testing, injectors are simply replaced with new or rebuilt parts. Who is right?

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

Question 48

Two technicians are describing safety when testing fuel injectors. Technician A says that the pressure from nozzle testers is high enough to penetrate skin, which can cause blood poisoning. Technician B says that you must never allow hands or skin to get near the tip of an injector nozzle and always wear eye protection. Who is right?

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

Question 49

Spray patterns can be first evaluated visually on a nozzle tester to determine whether the injector spray pattern is uniform and:

A)symmetrical"
B)straight"
C)circular
D)asymmetrical"

Question 50

Using which of the following, positioned beneath the nozzle, may also be helpful to evaluate spray angle and the uniformity of the spray pattern?

A)Another nozzle"
B)Catch basin"
C)Your hand
D)Piece of paper"

Question 51

Which of the following is not indicated by a distorted spray pattern?

A)Blocked or restricted spray hole"
B)Eroded nozzle tip"
C)Low opening pressure
D)Worn nozzle orifice"

Question 52

Two technicians are describing testing nozzle spray patterns. Technician A says that disconnect the high-pressure fuel line, then cap the nozzle fuel line inlet fittings by using protective plastic caps. Technician B says that you set up the nozzle pop tester by filling it with number 1 diesel fuel. Who is right?

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

Question 53

Two technicians are describing testing nozzle spray patterns. Technician A says that the spray should originate from each orifice, and the spray pattern from each orifice can be a different size and shape Technician B says to purge the nozzle tester of air by pumping the handle several times until clean fluid appears from the high-pressure line. Who is right?

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

Question 54

When testing a fuel injection nozzle using a pop tester, what do you listen for?

A)Chatter"
B)Clicking"
C)Sweeping
D)Snapping"

Question 55

Which of the following is not a symptom of nozzle defects?

A)Low power"
B)Misfire under load"
C)Rough engine operation after warm up
D)Blue exhaust smoke"

Question 56

Fuel leakage from the nozzle tip is called:

A)back leakage"
B)forward leakage"
C)nominal leakage
D)bias leakage"

Question 57

Two technicians are describing measuring NOP (Nominal Opening Pressure). Technician A says that the liquid spray leaves the nozzle tip with sufficient velocity to penetrate the skin and cause serious injury. Technician B says that injector NOPs vary according to the type of nozzle and the manufacturer's specifications. Who is right?

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

Question 58

A cylinder misfires under all load and speed conditions with burned piston crowns. Which of the following could be the cause?

A)Nozzle stuck open"
B)Nozzle stuck closed"
C)NOP (Nominal Opening Pressure) at 70-90% of minimum specification
D)Plugged orifices"

Question 59

A diesel engine is misfiring with light smoke, especially at idle, along with excessive combustion noise. Which of the following is the MOST LIKELY cause?

A)NOP (Nominal Opening Pressure) at 70-90% of minimum specification"
B)Nozzle stuck closed"
C)Tip leakage
D)Plugged orifices"

Question 60

When evaluating injector nozzles, a technician notes that the nozzle opening pressure is at 70-90% of minimum specification. Technician A says that this will result in the use of additional fuel. Technician B says that this will result in nozzle dribble. Who is right?

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