Injectors

visual inspection of a fuel injector valve removed during overhaul shows heat discoloration of the lower end of the valve. this is indicative of ____________________. a. valve leakage b. insufficient valve lift c. choking of nozzle holes d. return check valve leakage

A

a faulty injector in one cylinder of an operating diesel engine can be located by _______________________. a. cutting out individual injectors and noting engine performance b. checking lube oil temperature c. checking cam position d. using a timing light

a

differential type needle valves in diesel engine fuel oil nozzles, are closed directly by _______________. i. spring pressure ii. fuel oil pressure a. i b. ii c. eithehr d. neither

a

faulty operation if diesel engine injection nozzles can be directly caused by ___________________. a. water in the fuel oil supply b. excessive fuel nozzle holder cooling c. a distorted fuel spray pattern d. leakage past the plunger into the oil drain

a

most fuel injection nozzles are opened by _________________. a. fuel oil pressure b. a cam operated follower c. a spring loaded pressure plate d. timing gears keyed to the crankshaft

a

the ability of a fuel particle to travel into the combustion chamber before burning is called ___________________. a. penetration b. permanence c. turbulence d. atomization

a

the degree of fuel atomization in a diesel engine cylinder depends primarily on _________________. a. the size of the holes in the fuel nozzle b. timing of the pump c. supply pressure to the pump d. shape of the combustion chamber

a

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

a

when a nozzle tester is being used to test a closed type fuel injection nozzle, a clogged nozzle orifice will be indicated by a __________________. a. distorted spray pattern b. chattering sound when the nozzle closes c. squealing sound midway in the pump stroke d. popping sound when the nozzle opens

a

when the operating pressure of a diesel fuel injector is greater than that specified by the engine manufacturer the _____________________. a. quantity of fuel injected is decreased b. quantity of fuel injected will always be increased c. start of injection is advanced d. duration of injection will always be greater

a

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 change b. nozzle operation will be unaffected c. fuel will leak into the drain line d. fuel will not be delivered

a

which of the fuel nozzles listed requirese the least maintenance? a. pintle b. single hole c. multi hole d. open

a

a change in the degree of fuel atomization in a diesel engine greatly affects the ___________________. a. air turbulence b. fuel penetration c. fuel spray tip angle d. fuel injection rate

b

a change in the degree of fuel atomization in a diesel engine would most greatly affect ________________. a. air turbulence b. fuel penetration c. fuel spray angle d. fuel injection rate

b

a fuel injection valve opening at a pressure lower than normal will result in _______________________. a. late fuel injection b. early fuel injection c. high exhaust temperature from that cylinder d. decreased effective stroke from that injector

b

an incorrect spray pattern produced by a diesel engine fuel injection nozzle can be directly caused by __________________. a. incorrect fuel rack setting b. overcooling of the nozzle c. low firing pressure d. excessive lube oil temperature

b

differential needle valves used in fuel injectors are directly closed by _____________________. a. cam action b. spring force c. fuel oil pressure d. firing pressure

b

faulty operation of diesel engine fuel injection nozzles can be a direct cause of ______________________. a. excessive fuel nozzle holder cooling b. sediment in the fuel supply c. distortion of the fuel spray pattern d. improper atomization of the fuel

b

fuel oil discharged into the diesel engine cylinder is atomized at the _________________. a. turbocharger b. injector nozzle tip c. carburetor d. fuel oil pump

b

fuel oil penetration into the cylinder of a diesel engine is __________________. a. dependent on air turbulence b. reduced by finer atomization c. increased by finer atomization d. nonexistent in the precombustion chamber system

b

heat damage to fuel injection nozzles can be prevented by avoiding ____________________. a. excessive fuel oil temperature b. long periods of engine overload c. metallic contact between nozzles and cylinder heads d. hard carbon deposit and varnish on the nozzles

b

if it becomes necessary to clean the spray holes in a diesel engine fuel injector, you should use a suitable size piano wire and ____________________. a. gasoline b. carbon solvent c. degreasing compound d. strong detergent

b

if the coolant temperature is too low as it passes through internally cooled fuel injectors, the injectors can be damaged by _________________. a. water condensation in the fuel b. corrosion of the nozzle tip c. decrease in fuel oil viscosity d. inadequate lubrication of the needle valve

b

indirect cooling of fuel injector nozzle holders for diesel engines is accomplished primarily by _______________. a. heat conduction into the injected fuel oil b. heat conduction into the water jacket wall c. water circulation through passages in the holder d. fuel oil circulation through passages in the holder

b

proper atomization of fuel in diesel engine combustion chambers will ________________. a. affect the injection pressure b. improve combustion c. reduce compression pressure d. decrease power output

b

the amount of fuel injected into a diesel engine cylinder by a unit injector is controlled by _____________________. a. the firing pressure in the cylinder b. a metering helix inside he pump c. varying the physical length of the plunger stroke d. varying the clearance between the injector cam and the injector rocker arm

b

the minimum delivery pressure required for diesel engine fuel oil injection depends primarily on the ________________. a. degree of cylinder air turbulence b. firing pressure in the engine c. compression ratio of the engine d. duration of the combustion period

b

the spray holes in diesel engine fuel valves should be cleaned using carbon solvent and ___________________. a. diesel fuel b. a special cleaning wire c. a copper wire brush d. a shaved wooden dowel

b

which of the following statements concerning fuel atomization in a diesel emgime cylinder is correct? a. the greater the atomization the greater the penetration b. the greater the atomization the lesser the penetration c. the degree of atomization has nothing to do with the degree of penetration d. atomization and penetration are one and the same

b

which of the fuel systems listed combines the injection pump and the injection nozzle in one housing? a. common rail b. unit injector c. air injection d. hydraulic governing

b

a broken pint;e in a fuel injector usually causes ___________________. a. corrosion of the spray nozzle b. clogging of the orifices c. distortion of the spray pattern d. erosion of the valves

c

a change in the quality of fuel atomization by a diesel engine fuel injector would be caused by a/an ____________________. a. increase in engine speed b. increase in cylinder turbulence c. leaking needle valve d. reduction in cylinder turbulence

c

carbon deposit build up on the injection nozzle orifice is least likely to occur when using which type of fuel injector nozzle? a. hole b. multi hole c. pintle d. multi pintle

c

dirt lodged on the nozzle valve seat of a fuel injection nozzle will cause ________________. a. erosion and cratering of the nozzle orifices b. fuel leakage into the nozzle drain line c. fuel leakage before and after injection d. insufficient fuel delivery through that nozzle

c

distortion of the spray pattern of a nozzle or injector may be indicated by a/an ______________. a. high firing pressure b. overload of that particular cylinder c. smoky exhaust d. cooling water temperature rise

c

fuel droplets injected into a diesel engine cylinder must have adequate penetration to __________________. a. prolong the ignition delay period b. ensure the beginning of fuel injection c. thoroughly utilize the air charge d. allow controlled fuel combustion

c

fuel injectors used in heavy fuel oil systems are usually provided with cooling to reduce ____________________. a. cold corrosion of the nozzles b. fuel viscosity for better atomization c. carbon accumulation on the nozzles d. fuel detonation in the cylinders

c

if the needle valve in a fuel injection nozzle sticks open _______________. a. fuel will leak into the nozzle drain line b. no fuel will be delivered through the nozzle c. the nozzle will overheat d. injection lag will be increased

c

in a unit injector an upper helix and lower helix are machined in the lower part of the plunger for _______________. a. facilitating plunger rotation b. positioning the control sleeve c. variable beginning and variable ending of fuel injection d. eliminating injection lag

c

in a unit injector, an upper helix and lower helix are machined in the lower part of the plunger for ______________. a. facilitating plunger rotation b. positioning the control sleeve c. accurate metering of the fuel oil d. eliminating injection lag

c

the amount of fuel delivered by a unit injector is controlled by the __________________. a. camshaft b. main spring c. rack position d. engine speed

c

the breaking up of fuel as it enters a diesel engine cylinder is known as ________________. a. airification b. vaporization c. atomization d. gasification

c

to minimize the formation of carbon deposits on fuel injection nozzles you should __________________. a. avoid using liquid cooled nozzles whenever possible b. avoid low cooling water temperatures c. avoid prolonged overloading of the engine d. make certain the gasket seal between the nozzle and cylinder head is tight

c

which of the following statements concerning a closed type fuel injection nozzle is true? a. the hole type of a closed nozzle is self cleansing b. multi hole type nozzles are only suitable for use in engines with precombustion chambers c. most closed nozzles open by fuel oil pressure acting on the differential area of the needle valve d. the pintle type nozzles are most suspectible to carbon deposits building up in and around the orifice

c

which of the fuel injection systems listed uses a spring loaded differential spray needle valve and an individual pump for each cylinder? a. common rail injection b. air injection c. jerk pump injection d. distributor injection

c

a change in the degree of fuel atomization in a diesel engine cylinder has the greatest effect on the ____________________. a. cylinder air turbulence b. fuel spray angle c. fuel injection rate d. combustion in that cylinder

d

a defective injector nozzle in a propulsion diesel engine can cause __________________. a. engine power losses b. smoking due to unburned fuel c. high exhaust temperature readings d. all of the above

d

a distorted spray pattern from a fuel injector can cause _______________. a. high firing pressure b. corrosion of the nozzle tip c. low fuel pressure d. loss of power

d

a distorted spray pattern from a fuel injector can cause a diesel engine to have __________________. a. higher firing pressure b. more power output c. lower fuel pressure d. less power output

d

a leaking diesel engine fuel injector will cause ___________________. a. prolonged maintenance intervals b. improved atomization c. greater fuel economy d. incomplete combustion

d

a unit type fuel injector is used on a diesel engine to ________________. a. meter the fuel b. produce the proper fuel oil pressure c. atomize the fuel d. all of the above

d

fuel injector nozzles are usually of the multi orifice type with the number and placement of the holes arranged according to the _______________________. a. type of piston rings b. pressure of the fuel system c. size of the pump plunger spring d. design of the combustion chamber

d

fuel is admitted to a diesel engine through the __________________. a. intake valves b. carburetor c. exhaust ports d. injector nozzles

d

fuel supplied by each unit injector on a two stroke/cycle single acting diesel engine is directed into each cylinder at a very high pressure through the _________________. a. high pressure fuel line b. spill deflector c. check valve d. spray tip of the injector

d

heat damage to fuel injection nozzles on a small high speed diesel engines can be prevented by __________________. a. employing fuel oil as a cooling medium b. preventing hard carbon deposit on nozzle tips c. avoiding fuel oil temperature exceeding builder's specification d. ensuring good metallic contact between nozzles and cylinder heads

d

if a few injector spray holes become plugged, the result could be _________________. a. excessive surging at governed speed b. combustion knock under load c. poor fuel combustion d. all of the above

d

in a large main propulsion diesel engine, if an excessive amount of carbon has been found to be forming around the fuel injector nozzle holes, which of the following would correct this condition? a. increase fuel injection pressure b. increase fuel preheat temperature c. decrease load limit on the governor d. increase injector cooling water temperature

d

injectors for use with heavy fuel oil may be internally cooled by either water or light oil to ______________________. a. prevent heat corrosion to internal components b. increase fuel delivery rate and economy c. prevent preignition d. avoid carbonization of the nozzle tips

d

one problem resulting from a diesel engine fuel injector opening pressure being lower than specified by the engine manufacturer is that the ____________________. a. start of injection will always be retarded b. duration of injection will always be reduced c. quantity of fuel injected will always be decreased d. quantity of fuel injected tends to be increased

d

plugged spray holes in a diesel engine fuel injector will cause excessive smoking at idling speed, in addition to ___________________. a. damage to pistons or cylinder heads b. detonation throughout the load range c. preignition throughout the load range d. excessive smoking when the engine is under load

d

the dripping of fuel from an injector nozzle after injection terminates often results in ______________________. a. early combustion b. incomplete combustion and decreased fuel consumption c. decreased cylinder wall temperatures and increased exhaust gas temperatures d. coking and blocking of the fuel nozzles

d

the injection pressure of a hydraulic fuel injection nozzle can be increased by ____________________. a. increasing fuel oil booster pump pressure b. increasing the injector nozzle orifice size c. removing shims from under the nozzle spring d. increasing compression on the pressure spring

d

the major cause of problems occurring with fuel injection equipment is __________________. a. incorrect replacement of barrels and plungers of jerk pumps b. overheating of the nozzle orifices c. cracked pump housings d. dirt in the fuel

d

the principal hazard to personnel when using a diesel engine fuel nozzle tester is ___________________. a. electrical shock b. toxic fumes c. explosion d. blood poisoning

d

what is the term given to the process of breaking up fuel oil into very fine particles for better combustion? a. settling b. straining c. spraying d. atomization

d

when a nozzle tester is used to check the spray pattern of a diesel fuel injection nozzle, which of the following statements is true? a. the valve should normally begin to open at 1/2 the popping pressure b. the needle valve spring should always be removed first before testing c. the needle valve should remain open after the nozzle pops open d. a serious hazard of blood posioning exists if the fuel spray penetrates the skin of the operator

d

which of the following problems could cause a misalignment between the needle valve and nozzle in a fuel injection nozzle? a. a bent fuel needle b. a defective nozzle tip seat c. a distorted valve body d. all of hte above

d

you are testing a closed fuel injection nozzle using a nozzle tester. a pressure slightly less than design valve opening pressure is applied. if no fuel appears at the spray tip, the _____________________. a. nozzle orifices are too small b. nozzle orifices are eroded c. needle valve spring is defective d. needle vlave is operating properly

d