TM 5-3895-346-14
FUEL INJECTOR
ENGINE OVERHAUL
correct amount of fuel into the combustion chamber at exactly the right time depends upon this unit. Because
the injector operates against high-compression pressure in the combustion chamber, efficient operation
demands that the injector assembly is maintained in first-class condition at all times. Proper maintenance of
the fuel system and the use of the recommended type fuel filters and clean water-free fuel are the keys to
trouble-free operation of the injectors.
Due to the close tolerances of various injector parts, extreme cleanliness and strict adherence to service
instructions is required.
Perform all injector repairs in a clean, well-lighted room with a dust- free atmosphere. An ideal injector room is
slightly pressurized by means of an electric fan which draws air into the room through a filter. This pressure
prevents particles of dirt and dust from entering the room through the doors and windows. A suitable air outlet
will remove solvent fumes along with the outgoing air. Also, provide a source for 110-volt alternating current
electric power.
Provide the injector repair room with a supply of filtered, moisture-proof compressed air for drying the injector
parts after they have been cleaned. Use wash pans of rustproof material and deep enough to permit all of the
injector parts to be completely covered by the cleaning agent, usually clean fuel oil, when submerged in wire
baskets of 16-mesh wire screen. Use baskets that will support the parts so as to avoid contact with the dirt
which settles at the bottom of the pans.
Rags should never be used for cleaning injector parts since lint or other particles will clog parts of the injector
when it is assembled. A lint-free cleaning tissue is a good, inexpensive material for wiping injector parts.
When servicing an injector, follow the general instructions outlined below:
1. Whenever the fuel pipes are removed from an injector, cover the filter caps with shipping caps to keep dirt
out of the injectors. Also protect the fuel pipes and fuel connectors from the entry of dirt or other foreign
material.
2. After an injector has been operated in an engine, do not remove the filter caps or filters while the injector is
in the engine. Replace the filters only at the time of complete disassembly and assembly of an injector.
NOTE
In the offset injector, a filter is used in the inlet side only. No filter is required on the outlet side
(Fig. 35).
3. Whenever an injector has been removed and reinstalled or replaced in an engine, make the following
adjustments as outlined in Engine Tuneup.
a. Time the injector.
b. Position the injector control rack.
4. Whenever the engine is to be out of service for an extended period, purge the fuel system, then fill it with a
good grade of rust preventive (refer to Storage).
5. When a reconditioned injector is to be placed in stock, fill it with injector test oil J 26400. DO NOT use fuel
oil. Install shipping caps on both filter caps immediately after filling. Store the injector in an upright position to
prevent test oil leakage.
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