Chapter 30 Common Rail System 4th Edition

What is the function of the quill tube used in many diesel CR systems?

connects the rail high pressure pipes to the EHIs through the cylinder head

What component is used to control the actual rail pressure of a CR diesel fuel system?

rail pressure control valve

If actual rail pressure falls below desired rail pressure in a diesel CR system, which of the following should occur?

rail pressure control valve directs more flow to the rail

If the rail pressure limiter valve trips open in a typical CR fuel system, which of the following should be true?

rail pressure has exceeded the highest specified system pressure

When a CR high pressure line is removed for any reason, which of the following steps is required practice by many engine OEMs?

replace the high pressure line

How many pump cylinders are used in a Caterpillar CR system high pressure pump?

two

What is the normal peak rail pressure used by Caterpillar on its C7 and C9 CR fueled engines when the system is functioning properly?

27,550 psi (1,900 bar)

How many high-pressure pump elements are used on a Bosch radial piston pump fueling a six-cylinder engine with a CR (common rail) fuel system?

Three

How many plungers are used in the high pressure section of a Bosch radial piston pump?

Three

How many pumping elements are used on a Caterpillar CR high-pressure pump fueling a C7 engine?

Two

Which of the following best describes the electrical principle that makes a piezotype actuator on an EHI operate?

Reversibility of piezoelectric effect

Technician A says that CR EHIs with piezo actuators respond faster to energization by the injector drivers than those with solenoid actuators. Technician B says that current CR EHIs using piezo actuators tend to be slimmer and more compact than those with solenoid actuators. Who is correct?

Technician A only

Technician A says that EHI pressure at the beginning of an injection pulse should be closely equivalent to rail pressure. Technician B says that EHI pressure at the end of an injection pulse will have dropped off significantly. Who is correct?

Technician A only

Technician A says that an EHI with a Piezo actuator is capable of breaking up a single injection cycle into up to 7 separate pulses. Technician B says that during a CR EHI multipulse injection cycle, the pressure rises through each successive pulse. Who is correct?

Technician A only

Technician A says that most transfer pumps used on diesel CR systems are of the external gear type. Technician B says that most transfer pumps used on diesel CR systems use a non-positive pumping principle. Who is correct?

Technician A only

Technician A says that the first generation of diesel common rail (CR) systems was introduced on small bore diesel engines. Technician B says that CR fuel systems are unable to produce high enough peak pressures to fuel current large bore diesel engines. Who is correct?

Technician A only

Technician A states that most CR systems are capable of multipulse injection. Technician B states that although multipulse fuel injection events improve fuel economy, they tend to increase combustion noise, especially at start-up. Who is correct?

Technician A only

Technician A states that CR systems that use adaptive trim do not require reprogramming of injection quantity calibration data when EHIs are replaced. Technician B states that CR systems with adaptive trim routinely evaluate EHIs performance and can make minor adjustments to the fuel trim. Who is correct?

Technician B only

Technician A states that to purge a typical CR system, the line nuts on the pipes connecting the rail to the EHIs should be cracked and re-torqued to spec after priming. Technician B states that some OEMs suggest that high-pressure pipes on CR systems be used once only because the seats deform to seal when torqued. Who is correct?

Technician B only

When the control plunger in an EHI is energized, what should happen to the rail pressure charged to the injector?

Remains almost unchanged

In a Bosch CR fuel system, the rail could also be known as a

Accumulator

What is required to initiate the energization of a solenoid actuator on a typical CR EHI?

Around 100 volts

Which of the following are advantages of multipulse injection cycles?

Better fuel economy Lower cold-start emissions Lower noise levels

Technician A states that first-generation CR diesel fuel systems used solenoid actuators. Technician B states that some current CR diesel fuel systems use piezo injectors because they can be switched at higher speeds. Who is correct?

Both A and B

What force is used to hold a CR EHI nozzle valve in its closed and seated position?

Combined hydraulic and spring forces

Which of the following is another way of saying injection quantity calibration data?

E-trim codes Quick-response (QR) codes Fuel flow codes

Which of the following best describes the type of injectors used with CR fuel systems?

Electrohydraulic injectors (EHIs)

What type of fuel transfer pump is used on Caterpillar CR fuel systems that manage C7 and C9 engines?

External gear

What device on a typical CR system prevents constant fueling of a cylinder if one of the EHIs sticks in the open position

Flow limiter

What would happen if an EHI used on a Bosch CR fuel system stuck in an open position?

Flow limiter would limit fueling

What is used to lubricate the high pressure radial piston pumps used on most Bosch CR fuel systems?

Fuel

What type of high pressure pump do Caterpillar use in their CR fuel systems?

Inline piston

Technician A says that desired rail pressure in a CR fuel system is signaled by the rail pressure sensor. Technician B says that actual rail pressure in a CR fuel system is calculated by the ECM. Who is correct?

Neither A nor B

Technician A says that the ECMs used on commercial truck applications of diesel CR are networked on the CAN-C bus. Technician B says that the diesel engine ECMs used on automobile and light truck applications of diesel CR are networked by the J1939 bus.Who is correct?

Neither A nor B

How many high pressure pumps are required to fuel an inline 6-cylinder, CR-fueled engine?

One

What electronic principle is used in the rail pressure sensor fitted to most CR diesel fuel systems?

Piezo resistive

What is used to switch an electrohydraulic injector (EHI) used in a typical CR fuel system?

Pulse width modulated signal

Which of the following best describes the means by which the ECM drivers control the actuation of CR EHIs?

Pulse width modulation (PWM)

Which of the following best describes the type of pump used with typical Bosch CR fuel systems?

Radial piston

Which of the following is the key component used to signal actual rail pressure to the ECM?

Rail pressure sensor