808285 Volvo.Penta Screw

Fuel System
SCHEMATIC OF THE FUEL SYSTEM
1. Fuel priming pump. 2. Fuel transfer pump. 3. Fuel injection pump. 4. Precombustion chamber. 5. Fuel supply line. 6. Primary fuel filter. 7. Bypass valve for fuel transfer pump. 8. Air vent valve. 9. Fuel filters. 10. Fuel manifold.This engine has a pressure type fuel system. There is a single injection pump and injection valve for each cylinder. The injection pumps (3) are in the pump housing on the right side of the engine. The injection valves are in the precombustion chambers (4) in the top left side of the cylinder head.The transfer pump (2) sends fuel from the fuel tank to the primary fuel filter (6). The primary fuel filter (6) removes the larger dirt particles from the fuel. Fuel goes from the primary fuel filter (6) to the fuel filters (9). The fuel filters (9) remove the smaller dirt particles from the fuel. Fuel goes from the fuel filters (9) to the fuel manifold (10) in the pump housing. This manifold is the source of fuel supply for each injection pump (3). The injection pumps (3) send fuel through high pressure fuel lines to the injection valves. The injection valves change the fuel to the correct fuel characteristic (spray pattern) for good combustion in the cylinders.The transfer pump (2) can supply more fuel than is necessary for injection, so a bypass valve (7) is used to control the pressure of the fuel in the fuel system.An air vent valve (8) in the fuel system is used to remove air from the fuel system. Air is removed by opening the air vent valve and putting pressure to the fuel system with the priming pump (1). Put pressure to the fuel system until a flow of fuel, free of air bubbles, comes from the vent line.Fuel Injection Pump Operation
Injection pump plungers (3) and lifters (6) are lifted by cams on camshaft (7) and always make a full stroke. The force of springs (5) hold the lifters (6) against the cams of the camshaft.Fuel from fuel manifold (1) goes through inlet passage (2) in the barrel and then into the chamber above plunger (3). During injection, the camshaft cam moves plunger (3) up in the barrel. This movement will close inlet passage (2) and push the fuel out through the fuel lines to the injection valves.The amount of fuel sent to the injection valves is controlled by turning plunger (3) in the barrel. When the governor moves the fuel rack, the fuel rack moves gear segment (4) that is fastened to the bottom of plunger (3).
CROSS SECTION OF THE HOUSING FOR THE FUEL INJECTION PUMPS
1. Fuel manifold. 2. Inlet passage in pump barrel. 3. Pump plunger. 4. Gear segment. 5. Spring. 6. Lifter. 7. Camshaft.Hydra-Mechanical Governor
An oil pump gear (10), part of shaft assembly (11), provides immediate pressure oil for the servo portion of the governor. A sump in body assembly (12) provides immediate supply for the pump. A bypass valve (B), in the body assembly, maintains correct pressure for servo supply oil.When the engine is operating, pressure oil from the pump is directed through passage (6) in cylinder (5), to a space around sleeve (7) and through an oil passage in piston (9) to a groove around valve (8). When revolving weights (2) slow down (occurring when engine load increases), the weights move in allowing governor spring (1) to move valve (8) downward. When the valve moves downward, the oil passage in piston (9) opens to the pressure oil in the groove around valve (8) and pressure oil is now at the large area end of piston (9) and pushes the piston, valve (8) and shaft (15) downward. Shaft (15) pushes lever (13), moving fuel rack (14) forward thus increasing the amount of fuel to the engine.With more fuel, engine rpm increases until the revolving weights (2) again rotate fast enough to balance the force of the governor spring. The passage in piston (9) will be between the oil pressure groove and the oil drain groove in valve (8). The movement of piston (9), valve (8), shaft (15), lever (13) and fuel rack (14) stops and the engine rpm is the same as before. When engine load decreases, revolving weights (2) speed up and toes on the weights move valve (8) upward opening oil passage in piston (9) to the drain groove around valve (8). Oil pressure between sleeve (7) and piston (9) pushes the piston, valve (8) and shaft (15) upward which moves fuel rack (14) to decrease the amount of fuel to the engine and the rpm of the engine (and revolving weights) decreases. When revolving weight force again balances governor spring force, the rpm of the engine is the same as before.
GOVERNOR CROSS SECTION
1. Governor spring. 2. Flyweights. 3. Thrust bearing. 4. Seat. 5. Cylinder. 6. Oil passage. 7. Sleeve. 8. Valve. 9. Piston and valve assembly. 10. Gear. 11. Shaft assembly. 12. Body assembly. 13. Lever. 14. Fuel rack. 15. Shaft. A. Speed limiter (engines so equipped). B. Bypass valve.The engine is stopped by pushing the governor control past detent.An oil passage through the center of valve (8) has a small oil outlet near the top end of the valve to lubricate thrust bearing (3) under seat (4). The bearing surface of revolving weight assembly (2) drive gear receives lubricating oil from the oil around sleeve (7) through an opening in cylinder (5).Governor action will change if there is a loss in lubricating oil pressure; however, the governor still offers protection against engine overspeeding because the weight assembly is mechanically connected to the fuel rack. The mechanical connections make it possible to move the fuel rack to the SHUTOFF position by using the controls normally used to stop the engine.When the engine is started, speed limiter plunger (A) restricts the movement of the governor control linkage. When operating oil pressure is reached, the plunger in the speed limiter retracts and the governor control can be moved to the