CASE 8M6634 - Caterpillar

Primary Filter/Water Separator
The primary filter/water separator is located between the fuel tank and the priming pump.Fuel Priming Pump
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Hand fuel priming pumpThe pump has a plunger (25) which is manually operated in order to prime the fuel system. Air is removed from the fuel system to the fuel return line to the tank. The fuel transfer pump is located in the fuel injection pump.Note: Machines that are equipped with optional fuel filtering equipment have the hand fuel priming pump located on the primary fuel filter base.Secondary Fuel Filter
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The secondary fuel filter (15) is located after the priming pump. The filter is always before the fuel injection pump.Note: Certain machines are equipped with additional secondary fuel filters.Fuel Pump Assembly
The fuel pump assembly consists of a low-pressure transfer pump and a high-pressure fuel injection pump. The pump assembly is driven from a gear in the front timing case at half engine speed. The fuel injection pump has two pistons that are driven by a camshaft. There is a cam for each piston and each cam has three lobes. The fuel injection pump delivers a volume of fuel six times for each revolution. The stroke of the pistons is fixed. The injector will use only part of the fuel that is delivered by each stroke of the pistons in the pump. The solenoid for the fuel injection pump is controlled by the ECM in order to maintain the fuel manifold pressure at the correct level. The solenoid allows excess fuel to be diverted away from the fuel manifold and back to the tank. A feature of the fuel injection pump allows fuel to return to the tank continuously.Fuel injection Pump
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The fuel injection pump generates high pressure for the fuel system.The fuel output of the fuel injection pump is controlled by the ECM in response to changes in fuel pressure.Fuel Transfer Pump
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The fuel transfer pump is a serviceable component.The fuel transfer pump provides a relatively low fuel pressure to the fuel injection pump. The fuel transfer pump has a regulating valve in order to control the low pressure. The fuel transfer pump circulates fuel through the primary fuel filter and the secondary fuel filter. The fuel transfer pump has a fuel bypass valve in order to allow the low-pressure fuel system to be primed.Shutoff
The engine shuts off by interrupting the fuel supply. The ECM specifies the amount of fuel. The quantity of the fuel that is required by the ECM is set to zero.Control
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Electronic control for the fuel system (typical example)The ECM determines the quantity, timing, and pressure of the fuel in order to be injected into the fuel injector.The ECM uses input from the sensors on the engine. These sensors include the speed/timing sensors and the pressure sensors.The ECM controls the fuel pressure by increasing or decreasing the flow of fuel from the fuel injection pump. The ECM controls the timing and the flow of fuel by actuating the injector solenoid.The amount of fuel is proportional to