Fuel Systems
Which of the following diesel fuels is most commonly used to fuel highway trucks in North America? A. #2D clear B. #2D red C. #1D clear D. #2D blue
#2D clear
Current diesel fuel formulated for on-highway use and classified as Ultra Low Sulfur (ULS) is required to have what maximum sulfur content? A. 0.0015% B. 0.05% C. 0.500% D. 0.300%
0.0015%
Highest cylinder combustion pressures within an on highway diesel engine occurs ____________. A. 10-15 degrees before BDC B. at TDC C. 10-15 degrees after TDC D. 10-15 degrees before TDC
10-15 degrees after TDC
When a port helix metering pump is phased to a 4-stroke cycle engine, how many times does the engine rotate through one complete pump revolution? A. 1 revolution B. 180 degrees C. 2 revolutions D. 4 revolutions
2 revolutions
Which fuel has the highest btu output by volume? A. Kerosene B. 2-D ULSD C. Gasoline D. 1-D low sulfur
2-D ULSD
What is the grade number set by the ASTM for warm climate diesel fuel? A. 1D B. 4D C. 2D D. 5D
2D
In which of the following engine locations would ignition typically take place? A. 90 degrees ATDC B. 3 degrees BTDC C. 15 degrees ATDC D. 30 degrees BTDC
3 degrees BTDC
The N3 injector's spray-in pressure can reach ________ psi. A. 3500 B. 35,000 C. 42,000 D. 350
35,000
Common fuel pressure supplied by the supply pump is ________ psi. A. 35-55 B. 15-35 C. 25 35 D. 50-60
35-55
Modern fuel systems today are capable of developing injection pressures of up to? ____________. A. 20,000 psi B. 63,000 psi C. 37,000 psi D. 4000 psi
37,000 psi
What is the lowest CN value that any #1D or #2D fuel formulated for highway use can be legally sold at? A. 47 B. 40 C. 38 D. 45
40
Which fuel, based on cetane number, will combust sooner? A. 35 B. 40 C. 45 D. 30
45
Injectors within a multiple plunger injection pump system are connected through ____________. A. high-pressure fuel lines B. segment gear C. a wiring harness D. fuel lines
A. high-pressure fuel lines
A fuel module may include a ____________. A. filter B. hand primer pump C. fuel heater D. All of the above
All of the above
A fuel return check valve ____________. A. limits fuel pressure. B. prevents drain back C. flows fuel backto the fuel tank D. All of the above
All of the above
Diesel fuel additives may include but are not limited to ____________. A. Cetane booster B. Biocides C. De foamers D. All of the above
All of the above
Disadvantages to biodiesel use include ____________. A. poor infrastructure for distribution B. filter plugging C. high manufacturing costs D. All of the above
All of the above
High fuel system pressurization is required to ____________. A. overcome high cylinder pressures B. overcome short time for combustion process C. produce fine atomization D. All of the above
All of the above
IDI diesel pintle injectors require ________ for fuel mix and combustion. A. hot pre-chamber B. high pre-chamber turbulence C. venturi flow affect D. All of the above
All of the above
Injection pump fuel delivery lines are ____________. A. made of seamless steel tubing B. all the same length C. tapered on the ends D. All of the above
All of the above
Injector orientation (position) is critical for ____________. A. good combustion B. proper spray pattern C. proper air fuel mixture D. All of the above
All of the above
The shape of the delivery valve ____________. A. prevents fuel wave deflection B. prevents secondary injection C. retains residual pressure D. All of the above
All of the above
The time necessary for combustion of diesel fuel is directly related to ____________. A. fuel quality B. cylinder temperature C. atomization D. All of the above
All of the above
Which phase of fuel injection occurs first? A. Pre ignition B. Vaporization C. Atomization D. Combustion
Atomization
Which of the following values is used to measure the heat energy in a fuel? A. BHP B. CNG C. RON D. BTU
BTU
Which fuel system is one of the most commonly used today? A. Distributor pump B. Pressure timed C. Port helix D. Common rail
Common rail
What is the primary engine input sensor used to compensate or perform idle adaptation? A. Crankshaft sensor B. Intake temperature sensor C. Coolant temperature sensor D. Road speed sensor
Crankshaft sensor
Oxidized diesel fuel will take on a _________ color. A. Lighter B. Darker C. Reddish D. Clear
Darker
Which of the following components would be more likely to fail if LS (Low Sulfur) fuel were used instead of a ULS (Ultra Low Sulfur) fuel in a highway diesel engine manufactured after 2007? A. Diesel particulate filter (DPF) B. Exhaust gas recirculation (EGR) circuit C. Crankcase ventilation system (CVS) D. NOx reduction catalyst
Diesel particulate filter (DPF)
What is the purpose of the vertical slot machined into the pumping plunger? A. Fill the pumping chamber with fuel B. Drain the pumping chamber C. Remove weight from the plunger D. Balance pumping plunger movement
Drain the pumping chamber
What happens as the effective stroke of a pumping plunger is shortened? A. Fuel delivery increases B. Fuel delivery decreases C. Fuel delivery stops D. Fuel delivery remains the same
Fuel delivery decreases
What does "injection rate" refer to? A. Fuel injected in relation to engine piston speed B. Injection pressure C. Speed of injection D. Fuel injected in relation per crankshaft angle
Fuel injected in relation per crankshaft angle
What controls fuel rack travel? A. Governor action B. Fuel pressure C. Engine speed D. Plunger length
Governor action
When an engine's cylinder is underperforming or is low on power output, what will the engine's governor do? A. Increase RPM B. Increase air flow C. Increase fuel flow D. All of the above
Increase fuel flow
Adjusting nozzle spring tension will affect ____________. A. NOP B. POP C. ROP D. Both A and C
NOP
Which component holds the nozzle valve on its seat? A. Nozzle body B. Nozzle spring C. Nozzle check ball D. Fuel pressure
Nozzle spring
Where is the overflow valve or restricted fitting located? A. Inlet of fuel gallery B. Fuel fill feed circuit C. Outlet of fuel gallery D. Internal of the pump
Outlet of fuel gallery
To measure fuel pump outlet pressure, where is the pressure gauge installed? A. Outlet of the secondary filter B. After the primary filter C. At the fuel return line at tank D. After the return check valve
Outlet of the secondary filter
Advancing fuel timing is known to produce higher______________emissions? A. Particulate matter (P.M.) B. Carbon dioxide (CO2) C. Oxides of nitrogen (NOX) D. All of the above
Oxides of nitrogen (NOX)
Which one of the following is the timing strategy used for cold start conditions? A. Retard injection timing B. Maintain injection timing C. Advance injection timing D. None of the above
Retard injection timing
Technician A says that EHIs are ECM-controlled but are limited by hard value NOPs. Technician B says that EHIs are used with common rail (CR) diesel fuel injection systems. Who is correct? A. Both A and B B. Technician B only C. Technician A only D. Neither A nor B
Technician B only
Technician A says that diesel fuel droplets burn from the inside out. Technician B says that small fuel droplets heat up to their ignition temperature more rapidly than larger droplets. Who is correct? A. Technician A only B. Technician B only C. Both A and B D. Neither A nor B
Technician B only
Diesel low-pressure fuel lines must not be routed __________. A. through the cab interior B. through the wiring harness C. through the frame D. below the fuel filter inlet
through the cab interior
Which two factors define the droplet sizing emitted from a diesel fuel injector? A. pressure and flow area B. timing and charge pressure C. engine speed and load D. air flow and boost pressure
timing and charge pressure
High cylinder pressures equals high ____________. A. horse power B. torque C. engine RPM D. All of the above
torque
What is the correct method used to determine if water is present in a diesel fuel tank? A. drain tank and visually inspect B. use water detection paste on a probe C. add a dye penetrant fluid D. drain sump and send for lab analysis
use water detection paste on a probe
Which of the following is true regarding plunger effective stroke: A. varies with engine rpm B. it is constant C. varies with manifold boost D. varies with fuel requirement
varies with fuel requirement
The insignificant ___________ of diesel fuel excludes it from evaporative emission strategies. A. volatility B. flash point C. auto ignite point D. pour point
volatility
Which of the following terms describes the tendency of a liquid to vaporize? A. viscosity B. volatility C. combustibility D. condensivity
volatility
Excessive injector back leakage may be caused by ____________. A. worn nozzle valve (clearances) B. contamination C. misalignment D. All of the above
worn nozzle valve (clearances)
Which is the recommended tool when performing primary fuel system inspection? A. Sight glass B. Pressure gauge C. Pressure differential gauge D. Vacuum gauge
Vacuum gauge
What is the most destructive contaminate within a fuel? A. Water B. Dirt C. Asphaltenes D. Gel
Water
Where are the fill and spill ports located? A. Within the plunger B. Within the control sleeve C. Below the plunger D. In the barrel
Within the plunger
A burned piston crown could be related to ____________. A. excessive back leakage B. excessive NOP C. a nozzle stuck open D. excessive return fuel
a nozzle stuck open
Mixing alcohol with diesel fuel will ____________. A. raise the ignition point B. absorb and suspend water C. not ignite with diesel fuel D. increase lubricating characteristics
absorb and suspend water
A vacuum valve in a fuel cap lets __________. A. fuel out B. fuel in C. air out D. air in
air in
On highway, diesel fuel tanks __________. A. are pressurized B. are vented C. feature double-walled construction D. None of the above
are vented
A fuel with a high ignition temperature will ____________. A. not combust B. combust earlier C. combust later D. None of the above
combust later
The governor is connected to the ____________. A. driving vane B. unison gear C. pinion gear D. control rack
control rack
Biodiesel advantages include a ____________. A. decrease in oxides of nitrogen B. decrease in carbon dioxide C. increased heat energy D. All of the above
decrease in carbon dioxide
Residual fuel pressure in the fuel lines allows for ____________. A. decreased injection lag B. increased in injection lag C. higher system fuel pressure D. multiple injections within one cycle
decreased injection lag
As pressure increases in the injection circuit, what happens to the emitted droplet sizing? A. becomes less aerated B. decreases in size C. increases in size D. becomes more aerated
decreases in size
What should be used to diagnose an air-in-fuel condition in a diesel fuel sub-system? A. diagnostic sight glass B. ether C. mercury manometer D. on-board diagnostic software
diagnostic sight glass
A loose primary side fuel fitting will __________. A. leak fuel B. draw air C. have no affect D. None of the above
draw air
The split linkage of a mechanical diaphragm pump operates on a(an) ____________. A. eccentric cam lobe B. outlet valve C. inlet valve D. diaphragm
eccentric cam lobe
Identify the nozzle capable of soft (variable) opening pressures? A. pencil B. electrohydraulic C. pintle D. multi-orifii in EUIs
electrohydraulic
Diesel fuel is injected at the ____________. A. beginning of compression stroke B. beginning of intake stroke C. end of intake stroke D. end of compression stroke
end of compression stroke
Pressure of fuel delivery out of a positive displacement pump increases as ____________. A. road speed of vehicle increases B. engine R.P.M. increases C. filter restriction increases D. engine R.P.M. decreases
engine R.P.M. increases
A blackened injector body (not the tip) indicates____________. A. failed copper sealing washer B. over fueling C. not enough air in combustion area D. worn injector body
failed copper sealing washer
What is the advantage of piezo actuators over solenoid actuators? A. higher peak pressure potential B. faster response C. lighter weight D. lower cost
faster response
Pressurization of the fuel in the plunger area occurs when ____________. A. delivery valve unseats B. fill and spill ports are closed C. fill and spill ports are open D. None of the above
fill and spill ports are closed
Hydraulically balanced injector nozzles are closed by ____________. A. electrical force B. spring force C. fuel force D. None of the above
fuel force
The purpose of the primary fuel filter(s) is to protect the __________. A. return check valve B. fuel tank C. injectors D. fuel pump
fuel pump
As the fuel absorbs heat, ____________. A. ignition starts B. liquid fuel is formed C. fuel vapor is formed D. fuel droplets are formed
fuel vapor is formed
Fuel volume can be measured with a ____________. A. restriction gauge B. pressure gauge C. graduated cylinder D. sight glass
graduated cylinder
The delivery valve feeds fuel to the ____________. A. high-pressure fuel lines B. plunger C. fill port D. overflow valve
high-pressure fuel lines
A leaking injector nozzle seat is more evident at ____________. A. high idle B. idle C. no load D. full load
idle
Increasing the time the spill port is closed will ____________. A. decrease fuel quantity injected B. decrease effective stroke C. increase effective stroke D. decrease engine rpm
increase effective stroke
When pressure within the nozzle valve collapses (drains) in a hydraulically balanced nozzle, ____________. A. fuel returns to the rail B. injection begins C. fill cycle begins D. None of the above
injection begins
Which variable defines the actual size of fuel droplets emitted from a diesel injector? A. charging pressure B. number of multipulse events C. injection pressure D. orifii size
injection pressure
What state is atomized fuel in? A. liquid B. vapor C. aerated D. gas
liquid
Fat and waxes present in diesel fuel provide good __________. A. pour point B. ignition point C. lubricity D. cloud point
lubricity
Injection rate is measured in ____________. A. nanoseconds B. kilo seconds C. picoseconds D. milliseconds
milliseconds
Cylinder pressure increases rely on ____________. A. more air delivered B. high atmospheric temperatures C. more fuel delivered D. high RPM
more fuel delivered
What type of injector nozzles are used with today's direct injected engines? A. poppet and pintle B. mechanical and pneumatic C. multi-orifii and electrohydraulic D. pencil
multi-orifii and electrohydraulic
An injection pump is static timed when the engine is ____________. A. not running B. at idle speed C. high idle D. full engine load and rpm
not running
Which of the following terms is used to describe the anti-knock ability of a gasoline? A. cetane number B. octane rating C. oxidation stability D. fire point
octane rating
A disadvantage to biodiesel use is the increase in ____________. A. particulate matter B. carbon dioxide C. oxides of nitrogen D. carbon monoxide
oxides of nitrogen
A hand primer pump is plumbed _________ the transfer pump. A. parallel to B. after C. before D. in line with
parallel to
"Fuel gelling" is also known as ____________. A. pour point B. cloud point C. vitality point D. sear of lubricity
pour point
Which of the following fuel subsystem components would typically be located closest to the fuel tank? A. transfer pump B. primary filter C. secondary filter D. injection pump
primary filter
What is the reason for advancing injection timing as engine speed increases? A. real time available for combustion increases B. less air in engine cylinder C. more air in engine cylinder D. real time available for combustion decreases
real time available for combustion decreases
Why does retarding injection timing tend to produce higher HC emissions? A. reduces time available for combustion B. increases combustion temperatures C. increases injection lag D. increases ignition lag
reduces time available for combustion
Which of the following correctly describes atomization? A. change of state from liquid to gas B. condensation of a gas to a liquid C. reduction of a liquid to minute droplets D. change of state from gas to liquid
reduction of a liquid to minute droplets
To vary fuel quantity in each pumping chamber, most multiple plunger pumps rely on a ____________. A. fill port B. rotating plunger helix C. rotating barrel D. spill port
rotating plunger helix
In a typical fuel subsystem, which of the following is capable of entrapping the smallest particles suspended in the fuel? A. primary filter B. fuel/ water separator C. pre-strainer D. secondary filter
secondary filter
Which of the following components would NOT be under suction when the engine is running? A. fuel tank B. secondary filter C. primary filter D. pickup tube
secondary filter
End of injection occurs when the ____________. A. fill port is covered B. spill port is opened C. spill port is closed D. fill port opens
spill port is opened
What would double gasketing of a primary fuel filter most likely cause? A. no-start condition B. sucking air into fuel C. fuel leakage D. vapor lock
sucking air into fuel
Which component supplies fuel to a multiple plunger pump? A. Transfer fuel pump B. Charging galleries C. High pressure fuel pump D. Overflow valve
Transfer fuel pump
