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单选题
The amount of fuel delivered by a helical plunger fuel injection pump is controlled by （）
A
varying the pump discharge pressure
B
varying the pump return pressure
C
rotation of the pump plunger
D
rotation of the pump barrel
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考题
The plunger in a jerk pump is rotated until the release port is uncovered If the port remains uncovered all of the time, which of the listed operations will occur?A.No fuel will be deliveredB.The maximum effective stroke will be attainedC.The fuel delivered to the cylinder will be excessiveD.The injection nozzle will overheat and carbonize
考题
The amount of fuel delivered by a helical plunger fuel injection pump is controlled by ______.A.varying the pump discharge pressureB.varying the pump return pressureC.rotation of the pump plungerD.rotation of the pump barrel
考题
单选题The amount of fluid delivered by a helical pump can be regulated by （）.A
throttling the pressure lineB
changing the speed of the rotorC
either A or BD
None of the above is tree
考题
单选题In a jerk pump, the amount of fuel that will be forced through the spray nozzle on each upward stroke of the plunger depends on （）A
the pump supply pressureB
the slope of the fuel camC
how the plunger is rotatedD
the number of sleeve segments engaged with the rack
考题
单选题Movement of the pump control rack in a fuel injection system using individual plunger-type pumps （）A
changes the position of the fuel inlet portsB
changes the length of the pump strokeC
varies the quantity of fuel deliveredD
varies the compression of the delivery valve spring
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 plunger in the fuel injector pump, usually operated by a （）, is driven up and down when working.A
crankshaftB
camshaftC
piston rodD
rack and pinion
考题
单选题If the needle valve in a fuel injection nozzle sticks open （）.A
no fuel will be delivered through the nozzleB
the nozzle will overheat and crackC
time of injection will changeD
fuel will leak into the drain line
考题
单选题A common trouble with the fuel pump plunger or fuel valve spindle is （）.A
water leakageB
steam leakageC
oil leakageD
air leakage
考题
单选题On most diesel engines, the governor controls the output speed by （）.A
controlling the amount of fuel injected into the cylindersB
varying the speed of the turbochargerC
adjusting the compression ratioD
changing the timing of the fuel injection camshaft
考题
单选题As the plunger moves up, the ports are closed and the fuel （） and delivered to the injector nozzle at very high pressure.A
being compressedB
to be pumped upC
is pressurizedD
are built up
考题
单选题Diesel engine injection lag is caused by（）A
compressibility of the fuelB
high fuel oil supply flowC
scored plunger and barrel packingD
excessive air turbulence
考题
单选题In a unit injector the amount of fuel that will be forced through the spray nozzle on each stroke of the plunger depends on （）A
the pump supply pressureB
the slope of the fuel camC
how the plunger is rotatedD
the number of sleeve segments engaged with the rack
考题
单选题The amount of fuel delivered by a unit injector is controlled by the （）A
camshaftB
main springC
rack positionD
nozzle orifice size
考题
单选题The pump has a constant stroke and the amount of fuel delivered is regulated by rotating （） which has a specially arranged helical groove cut into it.A
the pump cylinderB
the pump camC
the pump plungerD
the pump miler
考题
单选题The ash content of a fuel oil is significant to the operating engineer because it （）A
is an indication of the amount of noncombustible material present in the oilB
indicates the quantity of energy released by burning a unit amount of the fuelC
is useful for determining proper atomization temperaturesD
reflects the overall thermal efficiency of the fuel oil service system
考题
单选题The ignition quality of a fuel oil is an important operational consideration because it（）A
indicates the amount of abrasive material in the fuelB
affects the starting ability of a cold engineC
determines the amount of fuel penetration engineD
affects the compression ratio of an operating engine
考题
单选题The amount of fuel injection into a diesel engine cylinder by a unit injector, is controlled by（）A
the firing pressure in the cylinderB
a metering helix inside the pumpC
varying the physical length of the plunger strokeD
varying the clearance between the injector cam and the injector rocker arm
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Faulty operation of diesel engine fuel injection nozzles can be directly caused by （）.A
water in the fuel oil supplyB
excessive fuel nozzle holder coolingC
a distorted fuel spray patternD
leakage past the plunger into the oil drain
考题
单选题The amount of expansion space to be left in a fuel tank when fuel oil is being received, is determined by the （）.A
quantity of fuel to be receivedB
flash point of the fuel as it is receivedC
fuel temperature as it is receivedD
viscosity of the fuel being received
考题
单选题An increase in the fuel injection pump discharge pressure can be caused by a/an （）A
leaking delivery valveB
excessive bearing end playC
plugged injector spray holeD
increased plunger stroke
考题
单选题Because of the close tolerances used in diesel engine fuel oil pumps, a worn plunger requires（）A
grinding the spare plunger to the barrelB
replacing the plunger and the barrelC
highly polishing both the plunger and barrelD
replacing plunger only
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Fuel is delivered into the combustion space by （）.A
a cooling systemB
a lubricating systemC
an electric systemD
an injection system
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