Deck 9: Pump-Line-Nozzle Injection Systems

Question 1

Hydraulic governors on opposed plunger injection pumps offer what advantages over mechanical governors?

A) Quicker response time.
B) Simplified design and reduced pump size.
C) Better reliability but at the cost of a more complicated design.
D) Better protection from engine runaway.

Answer 1

B

Question 2

What is the function of the rack and control sleeves in port-helix PLN systems?

A) To rotate the plungers in unison.
B) To hold plungers in place when fuel pressure is removed.
C) To rotate the plungers individually.
D) To hold the plungers in a static position.

Answer 2

A

Question 3

What is electronic governing of a PLN fuel injection system classified as?

A) Full authority system.
B) Distributed authority system.
C) Centralized authority management system.
D) Partial authority management system.

Answer 3

D

Question 4

Fuel retained in the high pressure pipes between pumping pulses is known as?

A) Recirculation fuel.
B) Dead volume fuel.
C) Re-pressured fuel.
D) Waste fuel.

Question 5

Inlet-metering, opposed-plunger distributor injection pumps rely on what for the lubrication of internal components?

A) Pressurized engine oil.
B) Injection pumps are pre-greased and sealed.
C) Lubricity of diesel fuel.
D) Pump components are silicone coated.

Question 6

In a port-helix injection system the period between port closure and NOP is described as?

A) Spill lag.
B) Ignition lag.
C) port closure lag.
D) Injection lag.

Question 7

In a port-helix PLN which of the following best describes plunger geometry?

A) The width of the plunger.
B) The length of the plunger.
C) The physical shape of metering recesses machined into the plunger.
D) The manner in which the plunger acts on the delivery valve.

Question 8

What are the three types of Pump-Line-Nozzle (PLN) fuel injection systems used in light duty diesel applications?

A) Port-helix, inlet-metering and spill-timing.
B) Port-helix, inlet-metering and sleeve-metering.
C) Port-helix, sleeve-metering and injection-metering.
D) Inlet-metering, sleeve-metering and injection-metering.

Question 9

What unwanted condition is prevented in port-helix PLN systems by holding residual line pressure at about two thirds of NOP?

A) Injection lag.
B) Injector dribble.
C) Pressure wave reflection.
D) Secondary injections.

Question 10

Most port-helix injection pumps on North American diesel engines are timed to which engine cylinder?

A) Always to cylinder 1.
B) Either cylinder 1 or 6
C) Always the highest numbered cylinder.
D) The cylinder closest to the pump.

Question 11

Why is the port closure setting in port-helix systems of critical importance to the diesel technician?

A) It sets injection timing.
B) It controls injection fuel pressure.
C) It precisely controls ignition timing.
D) It is used to control cylinder pressure.

Question 12

Technician A states opposed-plunger inlet-metering pumps such as the Roosa DB2 are still widely used in many countries. Technician B states that these types of fuel pumps have design limitations which preclude them from use in current light duty diesel engines. Who is correct?

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

Question 13

What are anti-back kick cams in port-helix metering pumps designed to eliminate?

A) Valve overlap.
B) Starting misfires.
C) Engine fuel flooding.
D) Reverse direction starting.

Question 14

What two types of governor classification are used in port-helix metering pumps?

A) Trim governors and spill governors
B) Maximum speed (MS) and controlled speed (CS)
C) Limiting speed (LS) and variable speed (VS).
D) Port closure (PC) and port opening (PO).

Question 15

What is the purpose of an altitude-pressure compensator? .

A) Eliminate smoking at higher altitudes.
B) Increase fuel pressure at higher altitudes.
C) Decrease fuel pressure at higher altitudes.
D) Enrich the fuel mixture at higher altitudes.

Question 16

What function does the governor or rack actuator perform on a port-helix PLN system?

A) Controls the collapse phase of the injection pulses.
B) Limits the pressure produced by the charging pump.
C) Governs the delivery valve.
D) Controls fuel quantity delivered by precise positioning of the rack.

Question 17

If resistance is encountered while installing a fuel injection pump to an engine, what should the technician do?

A) Remove the pump and check pump position and drive mechanism for problems.
B) Check for the correct pump version.
C) Install the pump by applying leverage against a solid engine component.
D) Rotate the engine slightly and continue installation.

Question 18

How does a technician adjust the advance mechanism spring tension on an inlet metering, opposed plunger pump? .

A) By using spring shims.
B) Using the spring tension trimmer screw adjustment.
C) By adjusting the PCM input to the spring adjust solenoid.
D) Indirectly by adjusting vane pump pressure.

Question 19

What two factors vary ignition lag?

A) Fuel pressure and engine RPM.
B) Fuel quality (CN value) and engine RPM.
C) Amount of fuel charge and compression temperature.
D) Fuel ignition quality (CN value) and compression temperature.

Question 20

In a mechanical governor what forces act on the thrust lever?

A) Centrifugal force and spring force.
B) Pneumatic and spring force.
C) Centrifugal and centripetal force.
D) Hydraulic and spring force.

Question 21

Technician A states combustion knock is usually caused by fuel system issues or low fuel CN values. Technician B states knock can be caused by ignition lag. Who is correct?

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