5031106 JOHNSON SCREW

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Diagram of the basic fuel system (typical example) (1) Injectors (2) Fuel injection pump (3) Fuel block (4) Air inlet heater (5) Secondary fuel filter (6) Fuel tank (7) Primary filter/water separator (8) Fuel priming pumpThe engine has a Bosch VP30 Fuel Injection pump. The Bosch VP30 is an axial piston distributor injection pump that is electronically controlled.
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Bosch VP30 fuel injection pumpThe axial piston distributor injection pump that is electronically controlled generates injection pressure for all cylinders in a single pump. The injection pump is responsible for the distribution of fuel to the fuel injectors. The injection pressure is generated by a piston. The piston is moving axially. The movement of the piston is parallel to the fuel injection pump shaft.When the engine is cranking, the fuel is pulled from fuel tank (6) through fuel filter/water separator (7) by the fuel priming pump (8) . When the fuel passes through the water separator, any water in the fuel will go to the bottom of the bowl. Fuel priming pump (8) sends the fuel at a low pressure to the secondary fuel filter (5) . From the secondary fuel filter (5) , the fuel passes through the fuel supply line to the fuel injection pump (2) . The fuel injection pump (2) sends fuel through the high-pressure fuel lines to each of the fuel injectors (1) . The injectors (1) spray atomized fuel into the cylinder.The fuel injection pump needs fuel for lubrication. The precision parts of the pump are easily damaged. The engine must not be started until the fuel injection pump (2) is full of fuel. 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:
A fuel filter is changed.
A fuel line is removed.
The fuel injection pump is replaced. Components of the Fuel injection System
The fuel injection system has the following mechanical components:
Primary filter/water separator
Fuel priming pump
Secondary fuel filter
Air inlet heater
Fuel injection pump
Fuel injectorsPrimary Filter/water Separator
The primary filter/water separator is located between the fuel tank and the priming pump. The primary filter/water separator has a rating of 10 microns.Fuel Priming Pump
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Fuel priming pumpThe pump has a lever which is manually operated in order to prime the fuel system. In order to release air from the system, the orifice in the cover of the fuel filter is in the inlet side of the filter. The orifice is connected to the fuel tank by the fuel return line from the fuel filter. The priming pump gives a head of pressure for the fuel transfer pump. The fuel transfer pump is located in the fuel injection pump. The priming pump operates on an eccentric lobe on the camshaft.Secondary Fuel Filter
The secondary fuel filter is located after the priming pump. The filter is always before the fuel injection pump. The filter has a rating of 4 microns.Air Inlet Heater
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.
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Air inlet heater (1) Electrical connection (2) Ball valve (3) Wire coil (4) Fuel inlet (5) Delivery valve holder (6) Ignition coilThe air inlet heater is installed in the inlet manifold in order to heat the intake air in cold weather. The air inlet heater is ignited by fuel.When the ignition switch is turned to the HEAT position or when the control switch is pushed and the fuel shutoff control is in the ON position, the electrical current is supplied to the electrical connection (1) . The electrical current flows to the wire coil (3) which causes the wire coil to become very hot. A small amount of fuel will flow through the fuel line when the engine is cranking.The air inlet heater ignites a controlled amount of diesel fuel in the intake manifold in order to heat the intake air to the engine. The air inlet heater uses electric current to cause a heater coil in the body to create heat. The heat causes the expansion of the delivery valve holder (5) which opens the ball valve (2) in order to allow the fuel to flow into the air inlet heater.The fuel is vaporized by the heat of the valve body. When the engine is cranked, the air is forced into the inlet manifold. The vapor is ignited by the ignition coil (6) . The heat from the combustion of the fuel heats the intake air.When the ignition switch is turned to the RUN position or the control switch is released, electric current stops to the air inlet heater. When the engine begins to run, the flow of air in the inlet manifold makes the air inlet heater cool quickly. The valve closes. This stops the fuel flow in the fuel supply line.Fuel Injection Pump
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Schematic of the Bosch fuel injection pump (1) ECM (2) Electronic control unit (ECU) for the injection pump (3) Fuel priming pump (4) Cam ring (5) Speed/timing sensor (6) Pressure regulator (7) Fuel solenoid valve (8) Fuel transfer pump (9) Timing mechanism (10) Roller (11) Cam plate (12) Delivery valve (13) Distributor plunger (14) Injector (15) Control valve for the advance and the retardingThe fuel injection pump has the following operations:
Delivery
Generation of high pressure
Distribution and injection
Timing
Shutoff
ControlDelivery