6222A 4 Mercury SWITCH BOX ASSEMBLY

Illustration 1 g06130587
(1) Pressure Limiter
(2) Common Rail Manifold
(3) Injection Pipes
(4) Rail Pressure Sensor
(5) Suction Control Valve (SCV)
(6) Check Valve
(7) Injector
(8) Engine ECM
(9) CAN Communication
(10) Machine ECM
(11) Supply Pump
(A) From Fuel Filter
(B) Return to Fuel Tank
(C) High-Pressure Fuel
(D) Low-Pressure FuelThis is a common rail fuel system, which is electronically controlled. The supply pump (11) pressurizes the common rail manifold (2).The common rail manifold has rail pressure sensor (4) to ensure proper fuel pressure in the common rail manifold. The common rail manifold also has a pressure relief valve (1) which only opens as an emergency relief. The common rail manifold provides high-pressure fuel to the four injectors via the high-pressure lines (3).The Engine ECM (8) controls the timing and amount of fuel the injectors inject.The Machine ECM controls the engine speed via CAN communication.Feed Pump
Illustration 2 g06130617
(1) Feed Pump
(2) Hand Priming Pump
(A) Suction Side
(B) Discharge Side
Illustration 3 g06130678
(3) Suction Side Check Valve
(4) Piston Spring
(5) Piston
(6) Suction Side Check Valve
(7) Tappet
(8) Fuel Cam
(9) Inner Chamber
(10) Discharge Side Check Valve
(11) Discharge Side Check Valve
(12) Outer Chamber
(13) Push Rod
(14) Fuel from Feed Pump to Supply Pump
(15) Supply Pump
(A) Suction Side
(B) Discharge Side
(C) Up Stroke
(D) Down Stroke
(Purple) Higher Pressure to Supply Pump
(Blue) Lower Pressure from Filter
Illustration 4 g06130685
(1) Feed Pump
(14) Fuel from Feed Pump to Supply Pump
(15) Supply Pump
(B) Eye BoltThe feed pump is installed on the engine and is separate from the high-pressure pump. The feed pump has a hand priming pump (2) which must be used to remove air from fuel system. Refer to the Machine's Operation and Maintenance Manual, Fuel System - Prime for the full procedure.The feed pump pulls fuel from the fuel filter and supplies it to the supply pump. This occurs during both the up and downstroke of the piston (5).When the fuel cam (8) moves upward as shown in (C), the tappet (7) , push rod (13), and piston (5) also move upwards. This increases the pressure in the inner chamber (9) and fuel flows to the supply pump. This is accomplished by the internal check valves. As the pressure in the Inner chamber (9) increases, that causes the suction side check valve (3) to close and discharge side check valve (10) to open. At the same time the outer chamber (12) pressure decreases so suction side check valve (6) opens and discharge side check valve (11) closes. This allows fuel to flow to the supply pump via eye bolt (B) and fuel line (14).When the fuel cam moves downward, the piston moves downward. This increases the pressure in the outer chamber (12) and fuel flows to the supply pump. This is accomplished by the internal check valves. As the pressure in the inner chamber (9) decreases, and suction side check valve (3) opens and discharge Side check valve (10) closes. At the same time the pressure in outer chamber (12) increases. This causes suction side check valve (6) to close and discharge side check valve (11) to open. This allows fuel to flow to the supply pump via eye bolt (B) and fuel line (14).Supply Pump
Illustration 5 g06131699
(1) Eye Bolt (Overflow Out)
(2) Eye Bolt (In from Feed Pump)
(3) Suction Control Valve (SCV)
(4) Overflow Valve
(A) Return to Fuel Tank
(B) To Common Rail Manifold
(C) From Feed Pump
Illustration 6 g06131718
(1) Eye Bolt (Overflow Out)
(2) Eye Bolt (In from Feed Pump)
(3) Suction Control Valve (SCV)
(4) Overflow Valve
(5) Zero Delivery Drain
(6) IO Valve
(7) Pressurizing Pump Body
(A) Return to Fuel Tank
(B) To Common Rail Manifold
(C) From Feed PumpThe 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 suction control valve (3), overflow valve (4), zero delivery drain (5), an IO valve (6).Suction Control Valve
Illustration 7 g06131745
(1) SCV Cylinder
(2) Solenoid
(3) Armature
(4) Piston
(5) Chamber
(A) Fuel from Feed Pump
(B) Fuel to Pressurizing PumpThe Suction Control Valve (SCV) increases or decreases the flow of fuel to the pressurizing pump body which controls the pressure in the common rail manifold. When the SCV solenoid is not energized fuel flows from the feed pump into port (A), into chamber (5) and out port (B) to the pressurizing pump body. When the SCV is energized the armature moves the piston to the left and closes off port (A) which decreases the flow to the pressuring pump body.
Illustration 8 g06131801
(a) Low Fuel Flow
(b) High Fuel Flow
(c) Current On
(d) Current Off
(e) High Current
(f) Low CurrentThe SCV is a proportional valve that adjusts the amount of delivered fuel.When common rail pressure does not need to increase pressure, then the SCV duty cycle is high as shown in (a). When the duty cycle is high the current is off occurs for a shorter time