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单选题
During the fuel injection period, fuel pressure must exceed cylinder gas pressure to （）.
A
ensure penetration and distribution of the fuel in the combustion chamber
B
ensure the needle valve is flushed clean during each injection
C
prevent combustion gas blowback into the open needle valve
D
prevent reflected pressure waves when the needle valve closes
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更多 “单选题During the fuel injection period, fuel pressure must exceed cylinder gas pressure to （）.A ensure penetration and distribution of the fuel in the combustion chamberB ensure the needle valve is flushed clean during each injectionC prevent combustion gas blowback into the open needle valveD prevent reflected pressure waves when the needle valve closes” 相关考题
考题
If fuel injection to a four-stroke/cycle diesel engine begins earlier than designed, ignition may be delayed because theA.cylinder compression pressure may not be high enoughB.cylinder compression temperature may be too highC.fuel oil injection pressure may not be high enoughD.scavenge and purge process is incomplete
考题
单选题When the opening pressure of a diesel fuel injector is greater than that specified by the engine manufacturer，the （）A
quantity of fuel injected is decreasedB
quantity of fuel injected will always be increasedC
start of injection is advancedD
duration of injection will always be greater
考题
单选题The primary function of a fuel delivery check valve assembly is to（）A
deliver proper fuel quantity to the injection nozzleB
provide rapid fuel injection cutoffC
control fuel quantity entering the pump bodyD
control fuel pressure delivered to the combustion chamber
考题
单选题The replacement piping for diesel engine high pressure fuel systems must be the same length and diameter as the original piping to （）.A
avoid unnecessary pints inventoryB
keep torsional vibration constantC
use existing supports and bracesD
maintain specified injection characteristics
考题
单选题A practical way of checking for excessive fuel injection in one cylinder of an operating diesel engine is to （）A
feel the high pressure fuel lineB
check the cylinder exhausts for white smoke frequentlyC
check the cylinder exhaust temperatureD
isolate each cylinder and inspect the injector
考题
单选题When the opening pressure of a diesel engine fuel injector is greater than that specified by the engine manufacturer, which of the following problems can be expected?（）A
Quantity of fuel injected tends to be decreasedB
Quantity of fuel injected will always be increasedC
Start of injection tends to be advancedD
Duration of injection will always greater
考题
单选题In the common rail system, excessive pressure in the header may be caused by （）A
improper adjustment of the bypass valveB
a dribble in the fuel injection nozzleC
insufficient leak-off through injection nozzle packingD
a malfunctioning injection nozzle
考题
单选题A fuel leak occurs in the high pressure fuel piping between the injection pump and fuel nozzleThis requires immediate repair because of the （）A
high cost of fuelB
serious fire hazardC
possibility of pollutionD
poor combustion which will occur in that cylinder
考题
单选题A drop in compression pressure in one cylinder of a diesel engine can be caused by（）A
a leaking fuel injection nozzleB
a clogged air filterC
early fuel injectionD
burned valves
考题
单选题The term “proper metering”, as applied to a diesel fuel injection system, can be best defined as （）.A
delivering the same quantity of fuel to each cylinder for each power stroke according to engine loadB
maintaining the metering adjustment for a reasonable period under all load conditionsC
timing fuel injection to obtain maximum power and good fuel economyD
distributing the fuel to all parts of the combustion chamber for proper combustion
考题
单选题The high pressure in fuel injection system of the diesel engine is produced by the （）.A
injector pumpB
fuel injectorC
governorD
turbocharger
考题
单选题If a diesel engine turned over at normal cranking speed but failed to start, the cause could be late fuel injection or （）A
excessive fuel pressureB
high lube oil viscosityC
inadequate fuel injectionD
excessive starting air pressure
考题
单选题The rate of fuel injection in a diesel engine cylinder depends primarily on （）.A
the size of the holes in the fuel nozzleB
timing of the pumpC
supply pressure to the pumpD
shape of the combustion chamber
考题
单选题Which of the listed set of conditions indicates early fuel injection timing?（）A
Loss of engine power and high exhaust temperaturesB
Higher than normal firing pressure and low exhaust temperaturesC
High fuel consumption and high exhaust temperaturesD
Lower than normal compression pressure and high exhaust temperature
考题
单选题Injection lag in a diesel engine may be caused by（）A
a higher cetane number of fuel oilB
the diesel fuel used having a high viscosityC
mechanical rigidity in the lube pump mechanismD
a decrease rigidity in the fuel pump delivery pressure
考题
单选题The amount of fuel delivered for each cycle must be in accordance with the engine load, and the same quantity of fuel must be delivered to each cylinder for each power stroke at that load.Which of the following statements describes this requirement?（）A
Proper timingB
Accurate meteringC
Suitable injection rateD
Suitable atomization rate
考题
单选题The longer the ignition delay period resulting from improper use of low cetane fuel, the （）A
less fuel will enter the cylinderB
higher the cylinder combustion temperatureC
more complete the fuel combustionD
more rapid the rise in combustion pressure
考题
单选题The longer the ignition delay period occurs in a diesel engine, the （）.A
less fuel will enter the cylinderB
lower will be cylinder compression temperaturesC
more complete will be fuel combustionD
more rapid will be the rise in combustion pressure
考题
单选题Which of the following problems may occur if the opening pressure of a fuel injection nozzle is greater than specified by the engine manufacturer?（）A
The amount of fuel injected will be increasedB
The start of injection will be retardedC
The nozzle will permit fuel to dribbleD
The spray pattern will be distorted
考题
单选题A fuel injection valve opening at pressure lower than normal will result in（）.A
late fuel injectionB
early fuel injectionC
high exhaust temperature from that cylinderD
decreased effective stroke from that injector
考题
单选题The purpose of the delivery check valve used in a diesel fuel injection jerk pump is to （）.A
assist in a quick cutoff of fuel injectionB
allow oil backflow from the injector to the helixC
reduce fuel oil pressure between injection strokesD
meter the quantity of fuel delivered
考题
单选题A diesel engine will lose power if fuel injection occurs too late in the cycle, because the（）A
fuel droplets will burn as they leave the fuel injectorB
fuel will not be properly atomized in the cylinderC
maximum expansion of the burned fuel cannot take place in the cylinderD
compression pressure will be too low to cause fuel ignition
考题
单选题The temperature of the fuel oil received during bunkering operations is critical in determining the（）A
expansion space to leave in a tankB
flash point at which the fuel will burnC
temperature to which the fuel must be heatedD
rate at which the fuel can be pumped during transfer operations
考题
单选题Fuel injection systems meter fuel, atomize fuel, and （）.A
create turbulence in the combustion chamberB
aid in completing cylinder scavengingC
inject fuel at the proper timeD
minimize fuel penetration into the cylinder
考题
单选题If the plunger or barrel of a fuel injection jerk pump becomes damaged,（）A
only the replacement of the entire pump would be acceptableB
the injection pump and injection nozzle must be replacedC
either the barrel or plunger must be replacedD
the barrel and plunger must be replaced as a unit
考题
单选题The rate of pressure rise during the period following fuel ignition in a diesel will result in （）A
valve overlapB
volumetric efficiencyC
turbulence of the air changeD
fuel efficiency
考题
单选题The minimum fuel oil delivery pressure required for diesel engine injection depends primarily on the（）A
degree of cylinder air turbulenceB
firing pressure in the engineC
quality of fuel to be injectedD
duration of the ignition delay period
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