Exam 13: Common Rail Fuel Systems

While performing a back leakage test for a second-generation Bosch CR fuel system, the fuel volume was measured to be above specification from the cylinder head. Technician A says the cause could be a leaking quill tube. Technician B says the cause could be one or more injectors with worn-out ball valve seats. Who is correct?

Consider a CR3 system with a leaking fuel return line. Which of the following situations is the operator most likely to encounter?

Technician A says that rate shaping involves changing the quantity of fuel as it is discharged from the injector spray holes. Technician B says that rate shaping requires multiple injection events and a high-pressure fuel system with the ability to vary injection pressure. Who is correct?

Which of the following will cause an injector to leak or to stay open and inject fuel continuously?

To reduce parasitic power losses produced by pumping fuel needlessly and to keep fuel temperatures low, pumps now use:

Technician A says that servo-hydraulic actuators that use electromagnets have better durability than piezoceramic actuators. Technician B says piezoceramic actuators are as durable as, if not more durable than, servo-hydraulic injectors that use electromagnets. Who is correct?

An electronically controlled fuel pressure regulator valve that varies pump _____ as commanded by the ECM regulates fuel supplied to the pump and maximum pump.

Consider a hydraulically balanced needle valve used in a first- or second-generation Bosch common rail (CR) injector. How would a drain orifice that is much larger than the inlet orifice affect its functioning?

Which one of the following is NOT a fuel return flow that can be measured to identify the faulty component?

Two technicians are explaining the Siemens injector operation. Technician A says that a piezoceramic actuator uses multiple stacked piezo crystal discs that expand longitudinally when electrically energized. Technician B says that fuel pressure in a chamber below the control piston regulates the movement of the control piston. Who is right?

Technician A says that cylinder misfires can be detected on CR engines by slightly cracking open the fuel line to each injector when the engine is running. Technician B says that it is important to place a shop towel over the injector when checking for misfires to prevent pressurized fuel from penetrating the skin. Who is correct?

Two technicians are discussing piezoceramic injectors. Technician A says that piezo technology involves replacing magnetic solenoids with high speed solenoids. Technician B says that piezoelectric crystals enable much faster injector response than do magnetic actuators. Who is right?

Which of the following is required for V engines to synchronize engine firing order with pump strokes?

To monitor and maintain the emissions levels to their current standard, what legislation requires manufacturers to detect any potential malfunction that could cause emissions to rise above legislated standards?

Consider a piezoelectric CR injector. What happens to the actuator when current is initially applied to the piezoceramic wafers?

Delphi claims the system can generate _____ reduction in emissions.

Technician A says that CRI2 injectors will amplify injection pressure under heavy loads as needed by the engine. Technician B says that injection amplification takes place only in CR3 injectors. Who is correct?

What typically happens to the length of the pulse width to the electronic fuel control valve (FCV) valve when fuel leaks from the high-pressure rail?

Consider a Bosch CRS2 system. The FCV on a CP-3 pump is open circuited. Which of the following conditions is most likely to be observed?

Consider a non-amplified CR injector. If the inlet restriction orifice to the pressure control chamber is plugged, what is the most likely to happen?