877614 Volvo.Penta Overhaul kit, sub unit

Fuel Flow
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. Bleed valve. 12. Fuel injection pump housing.Fuel is pulled from fuel tank (1) and through primary fuel filter (7) by fuel transfer pump (9). Priming pump (3) is used to fill the system with fuel and remove air from the system.Primary fuel filter (7), priming pump (3) and fuel transfer pump (9) make up the fuel supply pump.Fuel transfer pump (9) pushes fuel through secondary fuel filter (10) and into fuel injection pump housing (12).Fuel transfer pump (9) and bleed valve (11) maintain a fuel pressure of approximately 170 kPa (25 psi) inside fuel injection pump housing (12). The constant flow of fuel through the bleed valve helps to maintain a more constant fuel temperature and to remove air from the fuel system.Fuel injection pumps (6), one for each cylinder of the engine, are located in the injection pump housing. The fuel injection pump receives fuel from a manifold inside the fuel injection pump housing and pushes the fuel, at a very high pressure, through fuel injection lines (5) to fuel injection nozzle (4).Fuel that is not needed for injection flows out of the injection pump housing through bleed valve (11) and back to the fuel tank.The fuel injection nozzle injects the fuel, as a very fine spray, into the precombustion chamber.Fuel Supply Pump
FUEL SUPPLY PUMP
1. Fuel transfer pump. 2. Hand primer pump. 3. Primary filter.Fuel is drawn from the fuel tank and through primary filter (3) on the fuel supply pump. The primary filter removes foreign material from the fuel before the fuel moves to the hand primer pump or the fuel transfer pump.Hand primer pump (2) is screwed into the body of the fuel supply pump. The hand primer pump is used to fill the low pressure side of the fuel system with fuel and remove air from the system. For example, the hand primer pump should be used to fill the system and remove air when the secondary filter is changed.When the hand primer pump plunger is pulled up, fuel flows out of the primary filter and past inlet check valve (5). As the primer pump plunger is pushed down, the inlet check valve closes and the fuel is pushed past outlet check valve (6) into the low pressure side of the fuel system. When fuel is not pushed by the primer pump plunger, outlet check valve (6) is closed by a spring.The fuel transfer pump supplies low pressure fuel [approximately 170 kPa (25 psi)] to the fuel injection pump. Fuel transfer pump (1) is moved by a cam (eccentric) on the fuel injection pump camshaft. As the fuel injection camshaft turns, it pushes roller tappet (4) which pushes plunger (7) into the plunger chamber. Inlet check valve (5) is closed by its spring. Outlet check valve (6) is pushed open when fuel pressure in the plunger chamber is higher than the outlet check valve spring pressure. The fuel flows pass the outlet check valve and into the area behind the pump plunger. As the camshaft continues to turn, it lets the plunger spring push the plunger and roller tappet out of the plunger chamber. The fuel that was behind the plunger is pushed out of the supply pump by the pressure of the plunger spring. At the same time, fuel is pulled passed inlet check valve (5) and into the plunger chamber. The pump is now ready to start another cycle.
FUEL SUPPLY PUMP
1. Fuel transfer pump. 2. Hand primer pump. 3. Primary filter. 4. Roller tappet. 5. Inlet check valve. 6. Outlet check valve. 7. Plunger.Fuel Injection Pump
FUEL INJECTION PUMP
1. Constant bleed valve. 2. Fuel inlet. 3. Oil drain port. 4. Oil inlet port.The fuel injection pump sends an exact amount of fuel, at the exact time and at very high pressure to the fuel injection nozzle.Fuel flows from the secondary filter into fuel injection pump housing inlet (2). The fuel flows inside the injection pump housing to the four injector pumps. Fuel not needed to fill the injector pumps flows out of the pump housing through constant bleed valve (1) and back to the fuel tank. The constant bleed valve keeps the low pressure fuel inside the injector pump housing at approximately 170 kPa (25 psi).The fuel injection pump and governor use engine oil for lubrication. Lubricating oil enters the pump housing at oil inlet port (4).The oil lubricates the roller tappets and camshaft bearings. The oil flows through the camshaft roller bearing and into the governor housing. The oil level in the pump housing and governor housing is at the height of oil drain port (3). The fuel injection pump housing must be filled with engine oil before the engine is started.
FUEL INJECTION PUMP
5. Spill port. 6. Pump plunger. 7. Plunger barrel. 8. Control bar (rack). 9. Spring. 10. Sleeve. 11. Spring seat. 12. Lifter. 13. Cam. 14. Camshaft.The engine gear train turns fuel injection pump camshaft (14) at one half crankshaft rpm. As the camshaft turns, cam (13) raises lifter (12) and injection pump plunger (6). As the camshaft turns farther, spring (9) pushes spring seat (11) and the lifter against the cam. Spring seat (11) also pulls pump plunger (6) downward in the plunger barrel (7).The governor controls the amount of fuel the fuel injection pump must pump to the engine. The governor moves control bar (rack) (8) which turns control sleeve (10) which turns pump plunger (6). The length of each plunger stroke is the same. It is the position of the scroll on the pump plunger in relation to spill port (5) in plunger barrel (7) that controls the amount of fuel pumped by each stroke of the pump plunger.
PLUNGER AT BOTTOM OF STROKE
5. Spill port. 6. Pump plunger. 15. Spring. 16. Delivery valve. 17. Groove. 18.