F U E L S Y S T E MTM 5-3805-258-24-1S Y S T E M S O P E R A T I O NFUEL FLOWFUEL SYSTEMFUEL SYSTEM SCHEMATIC1. Fuel tank. 2. Fuel return line. 3. Priming pump. 4. Fuel injection nozzle. 5. Fuel injection line. 6. Fuel injection pump. 7. Primaryfuel filter. 8. Check valves. 9. Fuel transfer pump. 10. Secondary fuel filter. 11. Constant bleed valve. 12. Fuel injection pumph o u s i n g .Fuel is pulled from fuel tank (1) through primaryfuel filter (7) and check valves (8) by fuel transferpump (9). From the fuel transfer pump the fuel ispushed through secondary fuel filter (10) and to thefuel manifold in fuel injection pump housing (12). Abypass valve in the fuel transfer pump keeps the fuelpressure in the system at 170 to 280 kPa (25 to 40psi). Constant bleed valve (11) lets a constant flow offuel go through fuel return line (2) back to fuel tank(1). The constant bleed valve returns approximately34 liters (9 gal.) per hour of fuel and air to the fueltank. This helps keep the fuel cool and free of air.There is also a manual bleed valve that can be usedwhen the fuel priming pump is used to remove airfrom the system. Fuel injection pump (6) gets fuelfrom the fuel manifold and pushes fuel at very highpressure through fuel line (5) to fuel injection nozzle(4). The fuel injection nozzle has very small holes inthe tip that change the flow of fuel to a very finespray that gives good fuel combustion in the cylinder.FUEL INJECTION PUMPThe fuel injection pump increases the pressure ofthe fuel and sends an exact amount of fuel to the fuelinjection nozzle. There is one fuel injection pump foreach cylinder in the engine.The fuel injection pump is moved by cam (14) ofthe fuel pump camshaft. When the camshaft turns,the cam raises lifter (11) and pump plunger (6) to thetop of the stroke. The pump plunger always makes afull stroke. As the camshaft turns farther, spring (8)returns the pump plunger and lifter to the bottom ofthe stroke.3-3
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