885366T01 Mercury CHAP ASSEMBLY, Lower-Port

Engine Design
Bore ... 120.7 mm (4.75 in.)Stroke ... 152.4 mm (6.00 in.)Number of Cylinders ... 4Cylinder Arrangement ... *in-lineFiring Order (Injection Sequence) ... 1,3,4,2Direction of Rotation (when seen from flywheel end) ... Counterclockwise*No. 1 Cylinder is Opposite Flywheel End.
CYLINDER AND VALVE IDENTIFICATIONBore ... 120.7 mm (4.75 in.)Stroke ... 152.4 mm (6.00 in.)Number of Cylinders ... 6Cylinder Arrangement ... *in-lineFiring Order (Injection Sequence) ... 1,5,3,6,2,4Direction of Rotation (when seen from flywheel end) ... Counterclockwise*No. 1 Cylinder is Opposite Flywheel End.
CYLINDER AND VALVE IDENTIFICATIONFuel System
Introduction
The Fuel System is a pressure type fuel system. This system has an injection pump and an injection valve for each cylinder. The injection pumps are in the fuel injection pump housing on the right side of the engine. The injection valves are in the precombustion chambers in the cylinder head.The drive gear for the fuel transfer pump is on the front of the camshaft for the injection pumps.The governor controls the amount of fuel injected into the engine to maintain a desired rpm. The operator controls the speed (rpm) that is desired from the engine by moving the accelerator pedal. The accelerator pedal is connected by mechanical linkage to the governor control lever. The governor control lever is connected through mechanical linkage to both the fuel injection pump control bar (rack) and the rotating flyweight assembly.The flyweight assembly is connected to the fuel injection camshaft through a vibration dampening coupling. The flyweight assembly turns (rotates) at the same rpm as the fuel injection pump camshaft, that is one half engine rpm.Oil from the engine crankcase is the lubricant for the transfer pump, injection pump housing and governor.Fuel System Timing
Injection timing before TC (top center) is 20 2°.Fuel Flow
FUEL SYSTEM SCHEMATIC (TYPICAL EXAMPLE)
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 135 kPa (20 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 135 kPa (20 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 past 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 (TYPICAL EXAMPLE)
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 six injector pumps. Fuel not needed to fill the injector pumps flows out of the pump housing through constant bleed