单选题When disassembling or assembling an injection pump plunger and barrel you should （）Akeep the parts immersed in diesel fuelBalways keep the plunger and barrel togetherCwork over a linoleum-type surfaceDall of the above
单选题
When disassembling or assembling an injection pump plunger and barrel you should （）
A
keep the parts immersed in diesel fuel
B
always keep the plunger and barrel together
C
work over a linoleum-type surface
D
all of the above
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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
As the plunger moves upwards in the barrel, injection will commence once the plunger bas_______the spill ports and the pressure builds up.A.opened upB.closed offC.lined upD.taken off
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
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
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 injector pump is operated by a cam which drives the plunger （）.Atop and bottomBto and froCup and downDback and forth
单选题The plunger in the fuel injector pump, usually operated by a （）, is driven up and down when working.AcrankshaftBcamshaftCpiston rodDrack and pinion
单选题A common trouble with the fuel pump plunger or fuel valve spindle is （）.Awater leakageBsteam leakageCoil leakageDair leakage
单选题Diesel engine injection lag is caused by（）Acompressibility of the fuelBhigh fuel oil supply flowCscored plunger and barrel packingDexcessive air turbulence
单选题The fuel injector pump is operated by （） which drives the plunger up and down.Aa separate motorBa camCa generatorDa chain
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
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单选题An individual injection pump is designed for variable beginning and constant ending of injectionFor diesel engines operating at constant speeds, the start of injection will（）Aadvance as the load increasesBretard as the load increaseCremain unchanged regardlessDalways occur at top dead center
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Fuel injection uses the jet pump system and a Woodward type hydraulic （） is used to control engine speed.AcontrollerBgovernorCinstrumentDapparatus
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单选题In a common rail engine, the fuel is injected into cylinders（）Aby injection pumpsBat a time decided by the injection pump timingCby a signal opening the magnetic valvesDat a time decided by the cam directly
单选题When the follower is on the base circle of the cam, the pump plunger is at the （） of its stroke.AtopBmiddleCbottomDany of the above
单选题A centrifugal pump vibrates excessively during operationUpon disassembling the pump it is found that the impeller is out of balanceWithout an available spare, you should （）.Adrill holes through the heavy side of the impeller until it balancesBweld counterweights to the light side of the impellerCremove metal from the heavy side by machining in a latheDacid wash and serape the heavy side until it balances
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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
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