HUB AS 8V6382 - Caterpillar

Illustration 1 g00319028
Fuel System Schematic (1) Fuel tank (2) Fuel return line (3) Priming pump (4) Fuel injection nozzle (5) Fuel injection line (6) Fuel injection pump (7) Primary fuel filter (8) Check valves (9) Fuel transfer pump (10) Secondary fuel filter (11) Constant purge valve (12) Fuel injection pump housingFuel transfer pump (9) pulls fuel from fuel tank (1) through both primary fuel filter (7) and check valves (8). From the fuel transfer pump, the fuel is pushed through secondary fuel filter (10) and to the fuel manifold in fuel injection pump housing (12). A bypass valve in the fuel transfer pump keeps the fuel pressure in the fuel system at 170 kPa (25 psi) to 280 kPa (41 psi).Constant purge valve (11) allows a constant fuel flow through fuel return line (2) and back to fuel tank (1). The constant bleed valve returns approximately 34 L (9 US gal) per hour of fuel and air to the fuel tank. This helps keep the fuel cool and free of air. Fuel injection pump (6) receives fuel from the fuel manifold. Fuel injection pump (6) pushes fuel at a very high pressure through fuel line (5) to fuel injection nozzle (4). The fuel injection nozzle contains very small holes in the tip. The small holes change the flow of fuel to a very fine spray. This fine spray improves the fuel combustion in the cylinder.Fuel Injection Pump
Illustration 2 g00352392
Fuel Injection Pump (1) Check valve. (2) Inlet passage. (3) Fuel manifold. (4) Pump barrel. (5) Closed bypass port. (6) Pump plunger. (7) Slot. (8) Spring. (9) Scroll. (10) Spill port. (11) Lifter. (12) Fuel rack. (13) Gear. (14) Cam.There is one fuel injection pump for each cylinder in the engine. A fuel injection pump functions in two ways:
A fuel injection pump increases the pressure of the fuel.
A fuel injection pump sends a precise amount of fuel to the fuel injection nozzle.The fuel injection pump is moved by cam (14) of the fuel pump camshaft. When the camshaft turns, the cam raises the following components to the top of the stroke:
Pump plunger (6)
Lifter (11) The pump plunger always makes a full stroke. As the camshaft turns farther, spring (8) returns the same components to the bottom of the stroke.When the pump plunger is at the bottom of the stroke, any fuel at transfer pump pressure flows into inlet passage (2). This fuel flows around pump barrel (4) and to bypass port (5) .Fuel fills the area above the pump plunger.After the pump plunger begins the upstroke, fuel pushes out of the bypass port. Fuel pushes out until the top pump plunger closes the port. As the pump plunger continues to move up, the pressure of the fuel increases. At approximately 690 kPa (100 psi), check valve (1) opens. This allows fuel to flow through the fuel injection line to the fuel injection nozzle.As the pump plunger continues to move up, scroll (9) uncovers spill port (10). The fuel above the pump