Fuel System - Operation and Tests/Distributor Injection Pump CTM3274 (01JUL99) 220-3 Saran Liter Engines 060799 PN=342 FUEL SYSTEM OPERATION - DISTRIBUTOR INJECTION PUMP -UN-08MAR95 CD30333 1—Fuel transfer pump 4—Fuel injection nozzle 7—Fuel injection pump 8—Return fuel pressure 2—Fuel filter 5—Gravity pressure pressure 3—Fuel injection pump 6—Fuel transfer pump pressure The fuel transfer pump (1) draws fuel from the tank Incorporated into the fuel system is a means of and pressurizes it. This pressure permits the fuel to returning excess (or unused) fuel back to the fuel flow through the filter (2) and charge the transfer tank. Excess fuel comes from two sources:
pump of the injection pump (3). 1. Fuel injection pump: A quantity of fuel greater than With the fuel injection pump charged with fuel by the that required by the engine is supplied to the fuel fuel transfer pump, the injection pump plungers injection pump. pressurize the fuel to approximately 50000 kPa (500 bar; 7255 psi). Delivery (pressure) lines are 2. Fuel injection nozzles: A small amount of fuel used to route this high pressure fuel to the fuel seeps past the nozzle valve for lubrication purposes. injection nozzles (4).
To get the excess fuel back to the tank, a return line Fuel enters the injection nozzle at a pressure which from the injection pump is connected to the middle of easily overcomes the pressure required to open the the nozzle leak-off line. Fuel from both sources is nozzle valve. When the nozzle valve opens, fuel is then returned to the tank by a return pipe connected forced out through the orifices in the nozzle tip and to the front end of the leak-off pipe. atomizes as it enters the combustion chamber. CD,3274,G220,2 -19-04JAN99 220 3