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
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
相关考题：
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
Which of the following problems is the main source of fuel pump and injection system malfunctions?A.Improper lubricationB.Air in the fuel systemC.Coated fuel linesD.Excessive vibration
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
单选题The amount of fluid delivered by a helical pump can be regulated by （）.Athrottling the pressure lineBchanging the speed of the rotorCeither A or BDNone of the above is tree
单选题The main purpose of changing main engine to electronic controlled is not to（）Acontrol fuel injection time more preciselyBcontrol fuel injection rate more preciselyCmeet the environmental requirementsDmeet high engine speed requirements
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 （）Athe pump supply pressureBthe slope of the fuel camChow the plunger is rotatedDthe number of sleeve segments engaged with the rack
单选题Movement of the pump control rack in a fuel injection system using individual plunger-type pumps （）Achanges the position of the fuel inlet portsBchanges the length of the pump strokeCvaries the quantity of fuel deliveredDvaries the compression of the delivery valve spring
单选题The primary function of a fuel delivery check valve assembly is to（）Adeliver proper fuel quantity to the injection nozzleBprovide rapid fuel injection cutoffCcontrol fuel quantity entering the pump bodyDcontrol fuel pressure delivered to the combustion chamber
单选题If the needle valve in a fuel injection nozzle sticks open （）.Ano fuel will be delivered through the nozzleBthe nozzle will overheat and crackCtime of injection will changeDfuel will leak into the drain line
单选题A common trouble with the fuel pump plunger or fuel valve spindle is （）.Awater leakageBsteam leakageCoil leakageDair leakage
单选题Problems with the diesel engine fuel injection pump are usually caused by（）Aimproper adjustmentBcontaminated fuelCkinked fuel linesDexcessive engine vibration
单选题Which of the following problems is the main source of fuel pump and injection system malfunctions?（）AImproper lubricationBAir in the fuel systemCCoated fuel linesDExcessive vibration
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 （）Athe pump supply pressureBthe slope of the fuel camChow the plunger is rotatedDthe number of sleeve segments engaged with the rack
单选题The amount of fuel delivered by a unit injector is controlled by the （）AcamshaftBmain springCrack positionDnozzle orifice size
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.Athe pump cylinderBthe pump camCthe pump plungerDthe pump miler
单选题Injection lag in a diesel engine may be caused by（）Aa higher cetane number of fuel oilBthe diesel fuel used having a high viscosityCmechanical rigidity in the lube pump mechanismDa decrease rigidity in the fuel pump delivery pressure
单选题The amount of fuel injection into a diesel engine cylinder by a unit injector, is controlled by（）Athe firing pressure in the cylinderBa metering helix inside the pumpCvarying the physical length of the plunger strokeDvarying the clearance between the injector cam and the injector rocker arm
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?（）AProper timingBAccurate meteringCSuitable injection rateDSuitable atomization rate
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?（）AThe amount of fuel injected will be increasedBThe start of injection will be retardedCThe nozzle will permit fuel to dribbleDThe spray pattern will be distorted
单选题The purpose of the delivery check valve used in a diesel fuel injection jerk pump is to （）.Aassist in a quick cutoff of fuel injectionBallow oil backflow from the injector to the helixCreduce fuel oil pressure between injection strokesDmeter the quantity of fuel delivered
单选题The major cause of fuel pump and injection system problems is （）Aimproper adjustmentsBcontaminated fuelCkinked fuel linesDexcessive engine vibration
单选题The effective pump stroke of an individual port-and-helix fuel injection pump is determined by the （）Afuel delivery pressureBpump plunger diameterCplunger control rack positionDtotal pump stroke
单选题Faulty operation of diesel engine fuel injection nozzles can be directly caused by （）.Awater in the fuel oil supplyBexcessive fuel nozzle holder coolingCa distorted fuel spray patternDleakage past the plunger into the oil drain
单选题An increase in the fuel injection pump discharge pressure can be caused by a/an （）Aleaking delivery valveBexcessive bearing end playCplugged injector spray holeDincreased plunger stroke
单选题The major cause of problems occurring with fuel injection equipment is（）Aincorrect replacement of barrels and plungers of jerk pumpsBoverheating of the nozzle orificesCcracked pump housingsDdirt in the fuel
单选题If the plunger or barrel of a fuel injection jerk pump becomes damaged,（）Aonly the replacement of the entire pump would be acceptableBthe injection pump and injection nozzle must be replacedCeither the barrel or plunger must be replacedDthe barrel and plunger must be replaced as a unit
单选题The amount of fuel delivered by a helical plunger fuel injection pump is controlled by （）Avarying the pump discharge pressureBvarying the pump return pressureCrotation of the pump plungerDrotation of the pump barrel