36 Questions
What is the function of an electronic unit injector (EUI)?
Meters, pressurizes, and injects fuel directly into the combustion chamber
What is a key advantage provided by Electronic Unit Injectors (EUIs)?
Higher injection and spray-in pressure
What drives the unit injector in an engine with overhead cam-driven EUIs?
A dedicated camshaft lobe
What is the primary role of the poppet valve or spill control valve in a conventional unit injector?
Regulates the buildup of pressure inside the injector
What is the purpose of the electric solenoid or cartridge valve in a unit injector?
Controls the movement of the poppet valve
What is the fuel pressure range for the newest EUIs, such as the Delphi E3 electronic unit injector?
35,000-38,000 psi
What are the service advantages of Electronic Unit Injectors (EUIs)?
Adjustment-free design
What prevents fuel leakage in a conventional unit injector?
O-rings on the injector
What is the purpose of the spring-loaded plunger and barrel assembly in a unit injector?
Pressurizes fuel inside the injector
What is the function of the nozzle valve in a unit injector?
5-13 orifice holes with NOP of 3500-5000 psi
What is the role of the solenoid-actuated, electronically controlled spill valve in an electronic unit injector (EUI)?
Energizes the spill valve
What drives the injector in an engine with overhead cam-driven EUIs, resulting in the least amount of injection lag?
Overhead camshaft
What is the primary function of an electronic unit injector (EUI)?
Meters, pressurizes, and injects fuel directly into the combustion chamber
What is the purpose of the electric solenoid or cartridge valve in a unit injector?
Controls the movement of the poppet valve
What is the fuel pressure range for the newest EUIs, such as the Delphi E3 electronic unit injector?
35,000-38,000 psi
What is a key advantage provided by Electronic Unit Injectors (EUIs)?
Higher injection and spray-in pressure
What is the purpose of the spring-loaded plunger and barrel assembly in a unit injector?
Pressurizes fuel inside the injector
What is the primary role of the poppet valve or spill control valve in a conventional unit injector?
Regulates the buildup of pressure inside the injector
What is the role of the solenoid-actuated, electronically controlled spill valve in an electronic unit injector (EUI)?
Energizes the spill valve
What are the service advantages of Electronic Unit Injectors (EUIs)?
Faster repair times
What drives the unit injector in an engine with overhead cam-driven EUIs?
Dedicated camshaft lobe
What is the function of the nozzle valve in a unit injector?
Produces fine spray with multiple orifice holes
What prevents fuel leakage in a conventional unit injector?
O-rings on the injector
What drives the injector in an engine with overhead cam-driven EUIs, resulting in the least amount of injection lag?
Dedicated camshaft lobe
What regulates the injection timing and quantity of fuel in an electronic unit injector (EUI)?
ECM
What happens when the solenoid valve of the unit injector is energized?
Injector plunger pressurizes the fuel
What is the primary function of the spill control valve in a unit injector?
Regulate fuel injection timing and quantity
What drives the injector plunger in an engine with overhead cam-driven EUIs?
Camshaft
What occurs when the solenoid of the unit injector is deenergized?
Poppet valve opens, allowing fuel to drain back
What is the role of the nozzle valve in a unit injector during fuel injection?
Opens to allow pressurized fuel to enter the combustion chamber
What is the purpose of the fuel rail in a unit injector system?
Supply consistent fuel temperature between injectors
What is the function of the low-pressure fuel supplied to the injector during the suction stroke?
Fills the cavity created beneath the plunger
What is the role of the pressurized fuel in a unit injector system?
Forces the nozzle valve open for fuel injection
What is the significance of the energization time of the solenoid in a unit injector system?
A longer electrical signal generally translates into more fuel injected
What happens during the residual stroke in a unit injector system?
Fuel trapped beneath the plunger drains back
What is the effect of speed increase on the timing of actuating the solenoid in a unit injector system?
Timing needs to be delayed as speed increases
Test your knowledge about Electronic Unit Injectors with this quiz. Explore the history, functioning, and applications of EUIs in diesel engines. Learn about their role in achieving better fuel economy and meeting greenhouse gas emissions legislation.
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