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单选题
When a fuel injection nozzle overheats, which of the problems listed can be expected?（）
A
The fuel metering will vary
B
The fuel will explode
C
The cylinder head will crack
D
The engine will stop
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更多 “单选题When a fuel injection nozzle overheats, which of the problems listed can be expected?（）A The fuel metering will varyB The fuel will explodeC The cylinder head will crackD The engine will stop” 相关考题
考题
Because the timing of injection is crucial, _____ mounted on the camshaft, which is driven by the crankshaft are used to operate the fuel pumps, one of which is provided for each cylinder.A.gearsB.ramsC.barrelsD.cams
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
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
考题
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
_______can be a direct cause of faulty operation of diesel engine fuel injection nozzles.A.Excessive fuel nozzle holder coolingB.Sediment in the fuel supplyC.Distortion of the fuel spray patternD.Improper atomization of the fuel
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Heat damage to fuel injection nozzles on small high-speed diesel engines, can be prevented by（）A
employing fuel oil as a cooling mediumB
preventing hard carbon deposit on nozzle tipsC
avoiding fuel oil temperature exceeding builder’s specificationD
ensuring good metallic contact between nozzles and cylinder heads
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Fuels of different qualities may require advancing or retarding the injection timing, in addition to which if the injection timing is advanced when the engine is running at loads below the （）, then a saving in fuel can be achieved.A
BHPB
MCRC
IHPD
MEP
考题
单选题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
考题
单选题The knock occurring when a cold diesel engine is started and continues while running at low speed, but stops when the engine reaches normal operating speed and temperature, is（）.A
caused by retarded injection timingB
caused by a mechanical defect in one cylinderC
caused by high fuel injection pressuresD
normal for these conditions
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Dirt lodged on the nozzle valve seat of a fuel injection nozzle will cause（）A
erosion and cratering of the nozzle orificesB
fuel leakage into the nozzle drain lineC
fuel leakage before and after injectionD
insufficient fuel delivery though that nozzle
考题
单选题Which of the following is true about the fuel injection with an ordinary diesel engine?（）A
The process begins after TDCB
The process ends before TDCC
When the piston is near to the TDC the fuel injection endsD
None of the above is true
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Which of the following problems will occur if the needle valve in a fuel injection nozzle sticks in the open position?（）A
Fuel injection timing will changeB
Nozzle operation will be unaffectedC
Fuel will leak into the drain lineD
Fuel will not be delivered
考题
单选题Faulty operation of diesel engine fuel injection nozzles can be a direct cause of（）.A
excessive fuel nozzle holder coolingB
sediment in the fuel supplyC
distortion of the fuel spray patternD
improper atomization of the fuel
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In the cylinder of a diesel engine fuel is ignited by the（）A
spark from a plug in the pre-combustion chamberB
electrical discharge from the distributorC
heat of compression within the cylinderD
heat from the fuel injection nozzle
考题
单选题The major cause of problems occurring with fuel injection equipment is（）A
incorrect replacement of barrels and plungers of jerk pumpsB
overheating of the nozzle orificesC
cracked pump housingsD
dirt in the fuel
考题
单选题Which of the fuel injection systems listed uses a spring loaded differential spray needle valve and individual pump for each cylinder?（）A
Common-rail injectionB
Air injectionC
Jerk pump injectionD
Distribution injection
考题
单选题To minimize the formation of carbon deposits on fuel injection nozzles, you should （）A
avoid using liquid-cooled nozzles whenever possibleB
avoid low cooling water temperaturesC
avoid prolonged overloading of the engineD
make certain the gasket seal between the nozzle and cylinder head is tight
考题
单选题When restarting a heavy fuel diesel engine that has been stopped for some time, the engine should（）A
increase the starting air pressureB
use a higher than normal cranking speedC
increase the fuel injection pressureD
use a fuel having a lower ignition temperature
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When ship navigating in rough sea, the correct operation is （）A
navigating with a low diesel engine speedB
navigating with a stable diesel engine speedC
increasing the efficiency of propellerD
increasing fuel injection
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