ENGINEMAN 1 & CDuring the overhaul of fuel injection equip-ment, a spotlessly clean working space is essen-tial for the protection of all parts. Ideally, the areashould also be air conditioned. All air should bethoroughly filtered before it enters the space.Benches should have smooth tops. Metal-toppedbenches should be covered with linoleum or lint-free rags. Ample quantities of approved cleaningsolvent, of clean fuel oil, and of compressed airto blow parts dry, should be used to help ensurecleanliness during overhaul. Never use rags orwaste to clean injectors, as lint particles from themmay damage the injector parts.From the time a unit is removed from theengine until it is replaced on the engine, extremecare must be exerted to keep dust and dirt awayfrom all its parts. Before any connections areFigure 3-14.—A damaged and serviceable plunger.loosened, all dirt should be removed from theunit, tubing, and fittings by washing. Afterremoval of the unit from the engine, all opening(pump, nozzle, tubing, or injectors) should becovered with approved caps or coverings.Damage to the plunger of a fuel injectionpump or injector may be caused by such differentfactors as entry of dirt into the equipment, carelesshandling while the equipment is disassembled,corrosion,and improper assembly anddisassembly procedures.Dirt and water are responsible for practicallyall trouble encountered with fuel injection equip-ment. If the units are not properly protected, theycan be damaged beyond repair within a very shortperiod of operation. Remember that theclearances between the lapped surfaces are sosmall that occasionally extremely fine particles,such as dust from the atmosphere, are capable ofscoring these surfaces. Then small amounts ofwater that may collect from condensation will cor-rode these surfaces.An engine should never be operated unless thefuel has been properly filtered before reaching theinjection equipment. Although regular filters andstrainers are present in all fuel systems, in somesystems special safety filters or screens are incor-porated to further reduce the possibility of foreignmatter mixing with the fuel as it reaches the pumpand the injector. The location of these additionalsafety devices depends upon the system. In onesystem a screen is placed between the fuel transferpump and the fuel distributor, while in anothera filter is mounted directly on the pump.Because many surfaces of the parts of pumpsand injectors are lapped to extremely accuratefinishes, it is essential that they be HANDLEDWITH GREAT CARE. Parts that are droppedmay be bent, nicked, dented, or otherwiseruined. All work should be done well over thecenter of the bench. The use of a linoleum cover-ing will reduce casualties caused by dropping partson the bench. Never leave parts uncovered on thebench, but keep them immersed in diesel fuel untilhandled. Never handle lapped surfaces when theyare dry, as the perspiration on your hands maycause corrosion. Before a lapped surface ishandled, it should be immersed in clean dieselfuel, and the hands rinsed in clean fuel. Since themating parts of pumps and injectors are fitted toone another, such parts as plunger and barrelshould be kept together to avoid interchanging.Since water in the fuel, or improper storageof parts, can also cause CORROSION of the partsof a pump or an injector, all fuel should be cen-trifuged, and filter and strainer cases drainedperiodically to prevent excessive collection ofwater. Information on proper stowage proceduresshould be obtained from the appropriate technicalmanual.3-18
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