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单选题
Fix the fuel injector into （） after repair.
A
the cylinder liner
B
the cylinder cover
C
the cylinder jacket
D
the piston
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更多 “单选题Fix the fuel injector into （） after repair.A the cylinder linerB the cylinder coverC the cylinder jacketD the piston” 相关考题
考题
If you suspect a diesel engine is misfiring due to air leakage into the fuel system, you should begin looking for the leak at theA.fuel line connections to the cylinder injection valvesB.gasket surfaces of the fuel oil filtersC.discharge fittings of the fuel injector pumpsD.suction side of the fuel oil transfer pump
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Indirect cooling of fuel injector nozzle holders for diesel engines is accomplished primarily byA.heat conduction into the injected fuel oilB.heat conduction into the water jacket wallC.water circulation through passages in the holderD.fuel oil circulation through passages m the holder
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第一组Older loop scavenged engines may have a single injector mounted centrally in the cylinder head. Because the exhaust valve is in the center of the cylinder head on modern uniflow scavenged engines the fuel valves (2 or 3) are arranged around the periphery of the head. The pressure at which the injector operates can be adjusted by adjusting the loading on the spring. The pressures at which the injectors operate vary depending on the engine, but can be as high as 540 bar. Some injectors have internal cooling passages in them extending into the nozzle through which cooling water is circulated. This is to prevent overheating and burning of the nozzle tip. Injectors on modern engines do not have internal cooling passages. They are cooled by a combination of the intensive bore cooling in the cylinder head being close to the valve pockets and by the fuel which is re-circulated through the injector when the follower is on the base of the cam or when the engine is stopped. As well as cooling the injector, re-circulating the fuel when the engine is stopped keeps the fuel at the correct viscosity for injection by preventing it from cooling down. Fuel injectors must be kept in good condition to maintain optimum efficiency, and to prevent conditions arising which could lead to damage within the cylinder. Injectors should be changed in line with manufacturers recommendations, overhauled and tested. Springs can weaken with repeated operation leading to the injector opening at a lower pressure than designed. The needle valve and seat can wear which together with worn nozzle holes will lead to incorrect atomization and dribbling.Modern uniflow scavenged engines have______.A.a single injector mounted in the center of the cylinder headB.several injectors mounted around the external boundary of the cylinder headC.a single injector mounted at the external boundary of the cylinder headD.several injectors mounted in the center of the cylinder head
考题
Fuel is admitted to a diesel engine cylinder through the ______.A.injector nozzlesB.carburetorC.exhaust portsD.intake valves
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 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A leaking diesel engine fuel injector will cause（）A
prolonged maintenance intervalsB
improved atomizationC
greater fuel economyD
incomplete combustion
考题
单选题A sudden drop in diesel engine cylinder compression pressure can be caused by（）A
a leaking fuel injector nozzleB
a clogged air filterC
excessively early fuel injectionD
malfunctioning valves
考题
单选题The fuel injector injects a fine spray of fuel into the hot air and combustion （）, producing much high pressure in the gases.A
has begunB
takes placeC
occursD
happens
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 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
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单选题To successfully reduce an excessively high diesel engine exhaust gas temperature, you should （）.A
reduce the engine driven fuel pump outlet pressureB
retard the fuel injector timing to reduce powerC
increase the fuel rack settingD
reduce the load on the engine
考题
单选题The needle valve in the injector （） at a pre-set pressure which ensures that the fuel will atomize once it enters the cylinder.A
will liftB
will be liftedC
will closeD
will be closed
考题
单选题The （） in the injector will lift at a pre-set pressure which ensures that the fuel will atomize once it enters the cylinder.A
needle valveB
nozzlesC
pistonD
spring
考题
单选题A change in the quality of fuel atomization by a diesel engine fuel injector would be caused by a/an （）A
increase in engine speedB
increase in cylinder turbulenceC
leaking needle valveD
reduction in cylinder turbulence
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Indirect cooling of fuel injector nozzle holders for diesel engines is accomplished primarily by （）.A
heat conduction into the injected fuel oilB
heat conduction into the water jacket wallC
water circulation through passages in the holderD
fuel oil circulation through passages in the holder
考题
单选题A distorted spray pattern from a fuel injector can cause a diesel engine to have （）A
higher firing pressureB
more power outputC
lower fuel pressureD
less power output
考题
单选题One remedy for a high firing pressure, in addition to a high exhaust temperature in one cylinder of a diesel engine, is to （）A
increase scavenge air pressureB
reduce fuel booster pump pressureC
adjust the fuel rackD
retard fuel injector timing
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A sudden drop in compression pressure in one cylinder of a diesel engine can be caused by（）A
a leaking fuel injector nozzleB
a clogged air filterC
excessively early fuel injectionD
malfunctioning valves
考题
单选题If a few injector spray holes become plugged, the result could be （）A
excessive surging at governed speedB
combustion knock under loadC
poor fuel combustionD
all of the above
考题
单选题If you suspect a diesel engine is misfiring due to air leakage into the fuel system, you should begin looking for the leak at the （）A
fuel line connections to cylinder injection valvesB
gasket surfaces of the fuel oil filtersC
discharge fitting of the fuel injector pumpsD
suction side of the fuel oil tran
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