Exam 9: Functions of High Pressure Fuel Systems

Which of the following statements best describes ignition delay in a diesel engine?

After assembling an engine and discovering one of the vibration-insulating high-pressure fuel line clamps was missing, two technicians discussed potential consequences of the clamp remaining missing from the injector line. Technician A says that the line will crack due to vibration caused by pressure pulses. Technician B says that a single missing clamp on thick-walled steel lines will have no effect on the line. Who is correct?

Which of the following factors is NOT affected by injection rate control?

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?

Technician A says a slow buildup of the injection rate, which provides a ramp-shaped injection discharge rate shape for the main injection event and reduces CO emissions. Technician B says the ramp-shaped injection rate shape reduces NOx emissions. Who is correct?

Under load, higher cylinder pressures and temperatures cause fuel to burn more completely, and only _____ should be observed coming from the engine exhaust system.

In which of the following ways does the rate at which combustion occurs change when additional fuel is added to a cylinder?

What injection strategy is best used to start, but not run, a cold engine?

Which of the following is NOT provided by fuel and air mixed by bowl turbulence?

Which engine exhaust emission can be significantly reduced by using pilot injection (split-shot injection)?

What device regulates the quantity of fuel injected into the cylinders?

Since 2007, throttle plates are used to help in the operation of:

What minimizes the backflow of fuel into an injection system in order to maintain line pressure between injections?

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?

Consider an engine that is satisfactorily operating on all cylinders. If one cylinder is cut out for testing, what will happen to the pulse width (electrical signal time) of the remaining injectors?

While discussing possible causes of black smoke from the exhaust of an older heavy-duty diesel engine, Technician A says that black smoke from an engine under acceleration indicates the engine is producing plenty of power. Technician B says that smoke could indicate that the injector nozzle spray holes are worn out. Who is correct?

Newer diesel engines have about _____ holes as compared with only 4 or 5 in older engines.

Technician A says a long injector response time from a magnetic solenoid is due mostly to the speed of the electric current through long wire windings. Technician B says a long injector response time is caused primarily by heavy, high-inertia control valves. Who is correct?

The design of the delivery valve ensures fuel pressure drops far enough below nozzle opening pressure to prevent:

Diesel engines compress dense air mass that requires ________ to penetrate the dense compressed air with fuel.