Exam 9: Functions of High Pressure Fuel Systems

Two technicians are describing a mechanical fuel system. Technician A says that when the engine needs to rapidly accelerate, large injection quantities of high-pressure injection pressure are always available. Technician B says that small injection quantities distribute fuel too far and fast in the combustion chamber to provide the best combustion conditions. Who is right?

What is the process called where the liquid fuel is broken up into a fine mist?

Technician A says that the operator is the only system that determines engine power output. Technician B says that diesel governors have several inputs, but only the throttle is controlled by the operator. Who is right?

Technician A says that cutting out one cylinder at idle to check for a misfire condition will reduce idle speed by close to 100 rpm in a six-cylinder engine idling at 600 rpm if the cylinder is operating properly. Technician B says it is not possible to detect a misfiring cylinder at idle by noting a change in idle speed during cylinder cutout testing for any cylinder. Who is correct?

Fuel is injected only near the end of the compression stroke, so these events must be performed quickly to allow adequate time for:

Which of the following does NOT result in large fuel droplet size?

Higher pressurization produces increasingly smaller droplets of fuel that readily absorb heat and burn while improving atomization that results in efficient combustion, as well as:

Technician A says that when a diesel engine has an increased load and its speed remains constant, injection timing must advance. Technician B says that under those conditions, injection timing should retard. Who is correct?

How many separate injection events can HPCR (high pressure common rail) systems currently provide during one combustion cycle?

Under which of the following conditions is excessive particulate emissions NOT typically produced?

Technician A says that multiple injection events from an injector to reduce emissions results in less torque produced from an engine. Technician B says that multiple injection events during a combustion cycle are used to reduce heat loads in a cylinder. Who is correct?

Technician A says that fuel injection systems are electronically controlled with variable injection pressure capabilities and with maximum injection pressure reached independent of engine speed. Technician B says that improved atomization requires lower pressurization for improved emissions and performance. Who is right?

Technician A says that vibration isolators clamped to common rail fuel lines are necessary to prevent lines from cracking. Technician B says that fuel-injection lines can have different diameters and length. Who is right?

Speed and torque output are controlled by:

While checking contributions from each cylinder for a late-model electronically controlled engine, Technician A says that the purpose of adaptive cylinder balance is to reduce combustion noise so that diesels run more quietly. Technician B says adaptive balance reduces emissions and helps an engine run more smoothly. Who is correct?

What is the time period between the injection of fuel and its actual point of ignition called?

Efficient fuel systems must have the capability to change the point when fuel is injected, based on a variety of engine operating conditions and:

Improved atomization requires higher:

A slow buildup of the fuel-injection rate (ramp-shaped injection rate) for the main injection reduces which of the following emissions?

Which of the following is NOT a task performed by high-pressure injection systems?