TM 5-3805-262-344-2. FUEL INJECTORS MAINTENANCE This task covers disassembly, cleaning, inspection, reassembly, and adjustment offuel injector nozzles. It also includes a short theory of operation.THEORY OF OPERATIONFuel injectors consist of the items shown below.A measured quantity of fuel under high pressure moves from fuel injection pumpthrough inlet to high pressure channel in injector body. Fuel then moves throughvalve stop channel and enters pressure chamber which surrounds valve in injectortip.When pressure of fuel against valve is more than control spring force, valve ismoved from its seat at sac in injector tip. This permits fuel under high pressure toenter sac. Fuel then moves from sac through spray orifices to combustion chamber;fuel reaches combustion chamber in atomized condition.When fuel delivery stops, pressure against valve is decreased and control spring im-mediately returns valve to its seat; this removes danger of leakage after measuredamount of fuel has been released. Valve opens and closes rapidly with clear noise.During injection, a small amount of fuel leaks through controlled clearance betweeninjector tip and injector body; this leakage adds lubrication to all moving parts infuel injector. This fuel then moves through leak off channel, leak off fitting, leakoff lines and returns to fuel tank.4-78
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