TM 5-2410-241-23-1
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FUEL SYSTEM CONTINUED
Operation of the Electronic Unit Injector
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The operation of the Electronic Unit Injector (EUI) consists of the following four stages: pre-injection, injection, end
of injection, and fill. Unit injectors use a plunger and barrel to pump high pressure fuel into the combustion
chamber. Components of the injector include the tappet (Figure 7, Item 2), the plunger (Figure 7, Item 3), the barrel
(Figure 7, Item 4) and nozzle assembly (Figure 7, Item 5). Components of the nozzle assembly include the spring,
the nozzle check, and a nozzle tip. The cartridge valve is made up of the following components: solenoid (Figure 7,
Item 1), armature, poppet valve, and poppet spring.
The injector is mounted in an injector bore in the cylinder head, which has an integral fuel supply passage. The
injector sleeve separates the injector from the engine coolant in the water jacket. The engine uses a stainless steel
sleeve, which fits into the cylinder head with a light press fit.
Figure 7. Unit Injector.
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