8M0039464 Mercury RING, Retaining

Illustration 1 g00849199
Diagram of the basic fuel system (typical example) (1) Fuel injection nozzle (2) Fuel return line from fuel injection nozzle (3) Air inlet heater (4) Fuel return line from fuel filter (5) Fuel return line from fuel injection pump (6) Fuel supply line (7) Fuel filter (8) Fuel transfer pump (9) Water separator (10) Fuel injection pump (11) High pressure fuel lines (12) Fuel tankWhen the engine is cranking, the fuel is pulled from fuel tank (12) through water separator (9) by fuel transfer pump (8). When the fuel goes through the water separator, any water in the fuel will go to the bottom of the bowl. The fuel transfer pump sends the fuel at a low pressure to fuel filter (7). From the fuel filter, the fuel goes through fuel supply line (6) to fuel injection pump (10) .The fuel injection pump sends fuel through high pressure fuel lines (11) to each of fuel injection nozzles (1). The fuel injection nozzle sprays fuel into the cylinder. Fuel which is not used by the fuel injection pump goes through fuel return line (5) to the inlet side of fuel filter (7). Leakage from the fuel injection nozzles flows through the fuel return line from fuel injection nozzle (2) to the top of fuel filter (7), back to fuel tank (12), and through the fuel return line from fuel filter (4) .The fuel injection pump needs fuel for lubrication. The precision parts of the pump are easily damaged. For this reason, the engine must not be started until the fuel injection pump is full of fuel that is free of air.The system must be primed when any part of the system is drained of fuel. The following list contains examples of both service and repairs when you must prime the system:
The fuel filter is changed.
The fuel line is removed.
The fuel injection pump is removed.
Illustration 2 g00845968
Fuel system components (left side) (1) Fuel injection nozzle (2) Fuel return line from fuel injection nozzle (3) Air inlet heater (7) Fuel filter (10) Fuel injection pump (11) High pressure fuel lines (13) Fuel filter base (14) Fuel return line (15) Fuel supply line for the air inlet heater
Illustration 3 g00845981
Fuel system components (right side) (8) Fuel transfer pumpThere is a small filter screen in fuel transfer pump (8). The pump has a lever which is manually operated in order to prime the fuel system by removing the air. In order to release air from the system, the orifice in the cover of fuel filter (7) is in the inlet side of the filter. The orifice is connected to the fuel tank by the fuel return line from fuel filter (7).
If there is no fuel flow through the valve body of the air inlet heater, the fuel injection pump could be damaged. The fuel supply line to the air inlet heater must also be free of air in order to prevent damage.
An air inlet heater that is damaged will allow the fuel to drain into the inlet manifold when the engine is running. This condition could cause exhaust smoke. Excessive fuel could also cause an overspeed condition. An overspeed condition may result in severe engine damage.
The air inlet heater is an electrically operated device. The air inlet heater ignites a controlled amount of diesel fuel in the inlet manifold in order to heat the inlet air. A heater coil in the air inlet heater expands a delivery valve holder in order to allow the fuel to flow into the heater. The fuel is ignited by the hot coil. The combustion heats the air which passes through the inlet manifold when the starter motor is operated.Air inlet heater (3) is installed in the inlet manifold. The air inlet heater is controlled by a remote mounted control switch.Fuel Injection Nozzles
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Fuel injection nozzle (1) Fuel inlet (2) Fuel return line (3) Holder for the fuel injection nozzle (4) Fuel injection nozzle (5) Seat washer (6) OrificesNote: This fuel injection nozzle is not serviceable.Each fuel injection nozzle is fastened to the cylinder head by a gland nut on the holder for fuel injection nozzle (3). Fuel injection nozzles are not serviceable except for removal of fuel injection nozzle (4) in order to clean the orifice (6) .The operating pressure of the fuel injection nozzle is set and tested at the factory. Refer to Specifications, "Fuel Injection Nozzles" for the pressure settings of the fuel injection nozzles. The fuel injection pump forces the fuel to flow under high pressure to the hole in fuel inlet (1). The fuel then flows around a needle valve within fuel injector holder (3) which causes fuel injection nozzle (4) to fill with fuel. The pressure of the fuel pushes the needle valve and a spring. When the force of the fuel pressure is greater than the force of the spring, the needle valve will lift up.When the needle valve opens, fuel under high pressure will flow through nozzle orifices (6) into the cylinder. The fuel is injected into the cylinder through the orifices in the nozzle end as a very fine spray. When the fuel is injected into the cylinder, the force of the fuel pressure in the nozzle body will decrease. The force of the spring will then be greater than the force of the fuel pressure that is in the nozzle body. The needle valve will move quickly to the closed position.The needle valve has a close fit with the inside of the nozzle. This makes a positive seal for the valve.When the fuel flows to the cylinder, a small quantity of fuel will leak by the valve guide. This fuel lubricates the moving parts of the fuel injection nozzle. This fuel then goes through a passage in the holder for fuel injection nozzle (3) to fuel return line (2). This excess fuel is then returned to the fuel tank. Fuel Injection Pump
General Operation
The fuel injection pump is a pressurized system that is totally enclosed. The pump sends the correct