Exam 13: Common Rail Fuel Systems

At what ratio to engine speed is the high-pressure CP-3 pump driven?

Technician A says that during the end of injection stage, the pressure in the control chamber forces the control piston downward against the nozzle valve, seating the nozzle valve and ending injection. Technician B says that the ECM de-energizes the piezoceramic actuator to cause a rapid return of the actuator to a resting position during the end of injection phase. Who is right?

Two technicians are describing common rail fuel system operation. Technician A says that electronically regulating the pressure in the high-pressure pump permits injection pressures to vary with speed and load conditions. Technician B says that a common rail stores fuel pressurized to match optimal injection pressure for any given engine speed or load condition. Who is right?

What actuator technology is used with the Siemens VDO K16 pump?

Which of the following is an essential element of rate shaping, which refers to the quantity of fuel injected per degree of crankshaft rotation?

Current system pressures for heavy-duty CR injection operate as high as:

Which of the following fuel systems was developed by Bosch and used by Detroit Diesel's ACR (Amplified Common Rail) system?

At which stage of the Siemens injector operation does the larger surface area above the control piston apply greater pressure than the force of the fuel against the nozzle-valve annulus? ​

Technician A says that modern HPCR (High Pressure Common Rail) fuel pressurization occurs in concert with engine speed. Technician B says that regardless of engine rotational speed and load, HPCR fuel-injection pressure can be electronically controlled to provide the optimal pressure required. Who is right?

At which stage of the Siemens injector operation does spring pressure close the mushroom valve, causing pressure to build in the control piston control chamber?

To which generation does the high-pressure pump that Bosch purchased from Fiat in the mid-1990s belong, which can develop pressure up to 19,845 psi and was used in the Unijet System?

Which of the following operations is NOT used by Bosch CR1 and CR2 injectors to inject fuel?

In which of the following Bosch CRS2 injector stages does closing the drain orifice cause fuel pressure to build in the pressure chamber, forcing the control rod against the nozzle valve?

Two technicians are describing pressure control components of common rail fuel. Technician A says if the high-pressure pump is removed, timing marks on the pump gear and camshaft gear are used to correctly time components during reinstallation. Technician B says that late-model high-pressure pumps are often timed so the peak pressure pulses are phased with the injection events. Who is right?

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?

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?

In which of the 3^rd generation Bosch Piezo CRS3 injector stages is the nozzle valve hydraulically balanced with high-pressure fuel from the rail applied to the top and bottom of the nozzle valve?

Currently, the fastest production servo-hydraulic CR injector can produce ___ separate injection events during one combustion cycle.

Two technicians are describing measuring injector back leakage (method 1). Technician A says that you start and run the engine at idle, and for 5 minutes, measure and record the volume of fuel accumulating in the graduated cylinders. Technician B says that generally, a defective injector will flow three times the minimum return rate. Who is right?

How many main types of CR injectors are there?