Question 1

Pilot, main, and post-combustion injection events in the HEUI HIB-300 injector are controlled by the electrical signals to the:
A)spool valve"
B)poppet valve"
C)solenoid
D)intensifier"

Accepted Answer

The answer of Pilot, main, and post-combustion injection events in...

Question 2

When the spool valve opens, high-pressure oil is directed to the top of the _____ and then injection begins.
A)amplifier piston"
B)solenoid"
C)intensifier
D)poppet valve"

Accepted Answer

The answer of When the spool valve opens, high-pressure oil...

Question 3

Two technicians are describing HEUI HIB-300 injector operation. Technician A says that lifting the poppet valve opens a passageway, allowing pressurized oil above the nozzle valve to drain to a low-pressure oil return. Technician B says that a spool valve moves from side to side controlled only by magnetic forces. Who is right?
A)A only"
B)B only"
C)Both A and B
D)Neither A nor B"

Accepted Answer

Technician A is correct because lifting the poppet valve does open a passageway for pressurized oil to drain, which is part of the HEUI injector operation. Technician B is incorrect because the spool valve is not controlled only by magnetic forces; it is also influenced by hydraulic pressure.

Question 4

Two technicians are describing HEUI HIB-300 injector operation. Technician A says that fuel travels to the cavity above the amplifier piston while pressurized oil is applied to two sides of the poppet valve and to the top of the nozzle valve, holding it closed. Technician B says that when the poppet valve is energized, the valve lifts, closing off the high-pressure oil passageway and applying pressure to the nozzle valve. Who is right?
A)A only"
B)B only"
C)Both A and B
D)Neither A nor B"

Accepted Answer

The answer of Two technicians are describing HEUI HIB-300 injector...

Question 5

Which HEUI oil circuit does not pass through a filter, but instead connects the engine's main oil gallery to the reservoir?
A)High pressure supply"
B)Low pressure supply"
C)Short-circuit supply
D)Oil reservoir"

Accepted Answer

The short-circuit supply circuit connects the engine's main oil gallery to the reservoir, bypassing the filter.

Question 6

What prevents oil from draining back to the crankcase when the engine is not operated?
A)Oil filter"
B)Injectors"
C)Spool valve
D)One-way check ball"

Accepted Answer

A one-way check ball prevents oil from draining back to the crankcase by allowing oil to flow in only one direction, maintaining oil in the system when the engine is not running.

Question 7

Later designs of HEUI (hydraulically actuated electronic unit injection) systems corrected the problem of short-circuit oil supply by using oil filtered by the engine to supply the:
A)high-pressure circuit"
B)low-pressure circuit"
C)oil pan
D)oil pump"

Accepted Answer

Later designs of HEUI systems corrected the short-circuit oil supply issue by using engine-filtered oil to supply the high-pressure circuit, ensuring cleaner oil is used for injection.

Question 8

Reservoirs with a capacity of approximately ________ are incorporated into high-pressure pumps or cavities in the engine.
A)0.26 gallon"
B)0.50 gallon"
C)1 gallon
D)2 gallons"

Accepted Answer

Reservoirs with a capacity of approximately 0.26 gallon are typically used in high-pressure pumps or cavities in engines to ensure efficient operation and maintain pressure.

Question 9

Technician A says that during an oil change, oil can be drained from the accumulator or reservoir of a HEUI (hydraulically actuated electronic unit injection) system. Technician B says that reservoirs with a capacity of approximately 0.26 gallon (1 liter) are incorporated into high-pressure pumps or cavities in the HEUI engine. Who is right?
A)A only"
B)B only"
C)Both A and B
D)Neither A nor B"

Accepted Answer

Technician B is correct because HEUI systems often have reservoirs with a capacity of about 0.26 gallon (1 liter) incorporated into high-pressure pumps or cavities. Technician A is incorrect because oil is not drained from the accumulator or reservoir during an oil change in a HEUI system.

Question 10

Which device uses an electrically operated spool valve that moves in response to the strength of a magnetic field to control injector oil pressure?
A)High-efficiency pump (HEP)"
B)Injection control pressure regulator (ICPR)"
C)Injection control pressure (ICP) sensor
D)Oil pressure regulator"

Accepted Answer

The Injection Control Pressure Regulator (ICPR) uses an electrically operated spool valve that responds to a magnetic field to control the oil pressure for fuel injectors.

Question 11

What level of voltage do Gen II injectors require?
A)148 volts and 20 amps"
B)75 volts and 30 amps"
C)48 volts and 20 amps
D)115 volts and 8 amps"

Accepted Answer

The answer of What level of voltage do Gen II...

Question 12

What level of voltage do HEUI (hydraulically actuated electronic unit injection) A and B injectors require?
A)115 volts and 8 amps"
B)148 volts and 20 amps"
C)75 volts and 30 amps
D)48 volts and 20 amps"

Accepted Answer

The answer of What level of voltage do HEUI (hydraulically...

Question 13

Current used to energize the injectors is stored in:
A)TRC circuits"
B)RC circuits"
C)ECM (Electronic Control Module)
D)capacitors"

Accepted Answer

Capacitors are used to store electrical energy, which can then be used to energize the injectors in an electronic fuel injection system.

Question 14

Which module stores information such as engine firing order and operating and diagnostic software instructions?
A)ECM (Electronic Control Module)"
B)CCM (Computer Control Module)"
C)FICM (Fuel Injection Control Module)
D)ICM (Injection Control Module)"

Accepted Answer

The answer of Which module stores information such as engine...

Question 15

Two control signals from the ECM are supplied to the FICM (fuel injection control module): the fuel-delivery control signal (FDCS) and the:
A)cylinder identification (CID) signal"
B)engine position (CKP) signal"
C)camshaft position (CMP) signal
D)engine coolant temperature (ECT) signal"

Accepted Answer

The fuel-delivery control signal (FDCS) and the cylinder identification (CID) signal are two control signals from the ECM that are supplied to the FICM (fuel injection control module). The FDCS signal controls the amount of fuel that is delivered to the injectors, and the CID signal identifies which cylinder is currently firing.

Question 16

While diagnosing the cause of a hard start/prolonged cranking complaint, Technician A says that the high-pressure oil between the high-pressure pump and the injectors should stay pressurized for days. Technician B says the oil pressure to the injectors should quickly drop to zero when the engine is shut off. Who is correct?
A)Technician A"
B)Technician B"
C)Both A and B
D)Neither A nor B"

Accepted Answer

The answer of While diagnosing the cause of a hard...

Question 17

When replacing a HEUI (hydraulically actuated electronically controlled unit injector) injector, you inspect the condition of the inlet injector O-rings and find it nicked. Which of the following actions do you take?
A)Replace the O-ring"
B)Rebuild the injector"
C)Replace the injector
D)Replace all injectors"

Accepted Answer

The answer of When replacing a HEUI (hydraulically actuated electronically...

Question 18

Caterpillar uses a removable electrical jumper plug on C-7 and C-9 engines to correct actuation system variables when using either:
A)15W-40 or 10W-40 engine oil"
B)5W-40 or 10W-40 engine oil"
C)15W or 40W engine oil
D)10W-40 or 20W-40 engine oil"

Accepted Answer

The removable electrical jumper plug is used to adjust the actuation system variables for different oil viscosities, specifically when using 15W-40 or 10W-40 engine oil in C-7 and C-9 engines.

Question 19

Oil thickened by excessive soot loading will interfere with injector control valves operating properly, particularly in:
A)hot weather"
B)idle when hot"
C)cold weather
D)part-throttle"

Accepted Answer

In cold weather, oil thickened by soot can become more viscous, making it harder for injector control valves to operate properly.

Question 20

If Gen II injectors misfire, fail to deliver the correct quantity of fuel, are worn out or contaminated, or have sticking control valves, then they may need to be:
A)replaced"
B)rebuilt"
C)sent to a fuel shop
D)adjusted"

Accepted Answer

Gen II injectors may need to be replaced if they misfire, fail to deliver the correct quantity of fuel, are worn out or contaminated, or have sticking control valves.

Quiz 12: Heui Injection Systems

Pilot, main, and post-combustion injection events in the HEUI HIB-300 injector are controlled by the electrical signals to the:

When the spool valve opens, high-pressure oil is directed to the top of the _____ and then injection begins.

Which HEUI oil circuit does not pass through a filter, but instead connects the engine's main oil gallery to the reservoir?

What prevents oil from draining back to the crankcase when the engine is not operated?

Later designs of HEUI (hydraulically actuated electronic unit injection) systems corrected the problem of short-circuit oil supply by using oil filtered by the engine to supply the:

Reservoirs with a capacity of approximately ________ are incorporated into high-pressure pumps or cavities in the engine.

Which device uses an electrically operated spool valve that moves in response to the strength of a magnetic field to control injector oil pressure?

What level of voltage do Gen II injectors require?

What level of voltage do HEUI (hydraulically actuated electronic unit injection) A and B injectors require?

Current used to energize the injectors is stored in:

Which module stores information such as engine firing order and operating and diagnostic software instructions?

Two control signals from the ECM are supplied to the FICM (fuel injection control module) : the fuel-delivery control signal (FDCS) and the:

When replacing a HEUI (hydraulically actuated electronically controlled unit injector) injector, you inspect the condition of the inlet injector O-rings and find it nicked. Which of the following actions do you take?

Caterpillar uses a removable electrical jumper plug on C-7 and C-9 engines to correct actuation system variables when using either:

Oil thickened by excessive soot loading will interfere with injector control valves operating properly, particularly in:

If Gen II injectors misfire, fail to deliver the correct quantity of fuel, are worn out or contaminated, or have sticking control valves, then they may need to be: