885174 Mercruiser REGULATOR, Fuel Pressure

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(1) Fuel injectors (2) Electronic Control Module (ECM) (3) Sensors (4) Fuel rail (5) Fuel injection pumpThe fuel system of this engine is a common rail fuel system. This common rail system not only complies with strict emission regulations the system enables multiple, high-pressure injections that do not vary with engine RPM.The system is an electronically controlled fuel injection device with a supply pump (4) that pressurizes the fuel rail (5). Parameters are controlled by the ECM, such as the amount of fuel from the injectors and the timing, the pressure of fuel in the rail, as sensed signals from each sensor and CAN communications from the ECM. This results in fuel always being injected under ideal conditions, which suppresses the hallmark of a diesel engine, the black smoke during takeoff and acceleration. So there is less smoke, cleaner with a higher output of power.Supply Pump
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(1) Fuel temperature sensor (2) Suction control valve
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(2) Suction control valve (3) Delivery valve (4) Plunger (5) Suction valve (6) Regulating valve (7) Feed pump (8) Ring cam (9) Eccentric cam (10) ShaftThe supply pump is equivalent to previously used injection pumps and the pump delivers fuel to the rail at a pressure more than double that of previous pumps. The supply pump consists of a feed pump (12), a regulating valve (11), a suction control valve (7), pump unit, delivery valve (8), and a fuel temperature sensor (6) .Feed Pump
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(16) Outer rotor (17) Drive shaft (18) Inner rotor (A) Suction port (B) Supply from fuel tank (C) Discharge port (D) To pump chamberThe feed pump sucks up fuel filtered by the fuel filter and supplies fuel to the pump unit. The feed pump is a trochoid pump with an inner rotor (18) and an outer rotor (16), geared elliptically, the inner rotor is driven by the drive shaft (17) and drives the outer rotor in the same direction. In the process, the volume of the part enclosed by the teeth of the rotor changes and pumps the fuel.Regulating Valve
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(19) Pump housing (20) Feed pump (21) Bushing (22) Piston (23) Spring (24) PlugThe regulating valve controls the fuel feed pressure so the valve always stays at the set pressure. When the feed pressure exceeds the set pressure due to changes in the pump RPS, the piston (4) overcomes the pressure of the spring (23), opening the valve and returning fuel to the suction side of the feed pump.Suction Control Valve
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(25) Plunger (26) Feed pump (27) Regulating valve (28) Cylinder (29) Suction control valveBy regulating the amount of fuel supplied to the plunger, the suction control valve controls the pressure of fuel in the fuel rail. The suction control valve uses a linear solenoid valve and the fuel flow is controlled by how long the suction control valve is energized by the ECM.There are two types of suction control valves, the fail-open type "max flow with no power" and the fail closed type "min flow with no power". This engine uses a fail-open suction control valve.When power flows to the suction control valve, the actuator inside moves according to duty ratio, pressing the cylinder and altering the flow of fuel corresponding to the size of cylinder opening and establishing the appropriate amount of fuel.Fail-Open Type
With no power to the solenoid, the cylinder is returned via spring force and the valve opens wide, supplying a large quantity of fuel to the plunger.When the solenoid is energized, the armature presses the cylinder, compressing the spring and reducing the quantity of fuel supplied. The solenoid turns ON and OFF according to the duty ratio. The quantity of fuel supplied to the plunger is in proportion to the size of the cylinder opening.Duty Ratio Control
The engine ECM outputs a waveform signal for a set interval. The current amperage is the average amperage of the average current differential. When this average value rises, the size of the valve opening is reduced, and conversely, when dropped, the valve opens wider.When the SCV operates for a short time
The average current to the solenoid is low, so the cylinder is returned via spring force and the valve opens wide, supplying a large quantity of fuel to the plunger.When the SCV operates for a long time
The average current to the solenoid is high, so the armature presses the cylinder, compressing the spring, closing the valve opening and supplying a smaller quantity of fuel to the plunger.Pump Unit
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(30) Eccentric cam (31) Ring cam (32) Plunger (33) Drive shaftThe pump unit works to increase the pressure of fuel received from the SCV and is composed of a drive shaft, ring cam, and two plungers. A ring cam is mounted on the outside of the eccentric cam, which is on the same axle as the drive shaft, the plungers are arranged symmetrically vertically on the ring cam.When the drive shaft rotates, the eccentric cam rotates eccentrically and the ring cam is driven up and down by the