878187 Mercury SENSOR ASSEMBLY, Knock

Illustration 1 g06471531Reference: For more information, refer to the supplemental video "C9.3B Engine Fuel System Operation" on Caterpillar Channel1.Note: Click or copy the following link into a web browser (a CWS login is required to access Caterpillar Channel1), or scan the following QR code using a QR enabled device.https://channel1.mediaspace.kaltura.com/media/t/1_491jvxfj
Illustration 2 g06523376Fuel System Operation
Illustration 3 g06585951
(1) Tank
(2) 4um Tank Breather
(3) Primary Fuel Filter/Water Separator
(4) Diverter Valve (If equipped)
(5) Safety Valve
(6) Priming Bypass
(7) ECM
(8) Secondary/Tertiary Fuel Filters
(9) Fuel Pressure Sensor (secondary filter outlet)
(10) Fuel Pressure Sensor (secondary filter inlet)
(11) High-pressure Fuel Pump
(12) Fuel Transfer Pump
(13) Inlet Metering Valve
(14) High-pressure Fuel Rail
(15) Pressure Relief Valve
(16) Fuel Injector
(17) ARD Fuel Manifold (If equipped)
(18) Fuel Cooler (If equipped)The operation of this fuel system is different from any other type of fuel system that is actuated mechanically. The fuel system is free of adjustment. Adjustments to the components that are mechanical cannot be made. Changes in performance are made by installing different software on the ECM (7).This fuel system consists of five major components:
High-pressure fuel pump (11)
ECM (7)
Fuel Injectors (16)
High-pressure fuel rail (14)
Fuel transfer pump (12)Note: The components of the fuel system are not serviceable. These fuel system components cannot be disassembled. Disassembly will damage the components. If the components have been disassembled, Caterpillar may not allow a warranty claim or Caterpillar may reduce the warranty claim.The transfer pump (12) pulls fuel from the fuel tank (1) through the 10 micron primary fuel filter (3). The fuel transfer pump sends the fuel through the fuel cooled ECM (7), the 4 micron secondary and tertiary fuel filter (8) to high-pressure fuel pump (11). Fuel pressure sensor (10) measures the fuel pressure at the inlet of the secondary fuel filter. Fuel pressure sensor (9) measures the fuel pressure that is entering the tertiary filter. The high-pressure fuel pump pressurizes the fuel that is sent to the fuel rail (14). The fuel rail distributes the fuel to the fuel injectors (16) through fuel lines. The fuel rail uses a sensor that tells the ECM the pressure in the fuel rail. The ECM controls the solenoids for the high-pressure fuel pump to obtain the correct amount of pressure. If pressure at the fuel rail is too high, the pressure relief valve (15) opens. This valve drains the excess fuel back to the fuel tank. The rail pressure can vary from 42 MPa (6092 psi) to 190 MPa (27557 psi). Once fuel reaches the injectors, the ECM sends current to the injector solenoid to actuate the solenoid. Fuel flows from the high-pressure line to the injector tip. The injector bypasses any excess fuel back to the tank. The safety valve (5) prevents over-pressure downstream of the fuel transfer pump in the event of a significant downstream blockage or restriction. The priming bypass (6) allows fuel to flow past the fuel transfer pump during priming.Aftertreatment Fuel Supply (If Equipped)
Fuel is supplied to the aftertreatment system by fuel diverter valve (4) (if equppied) that is contained in the primary fuel filter system. The fuel diverter valve will send fuel to ARD fuel manifold (17) when needed.Component Description
Engine Control Module (ECM)
Illustration 4 g06236291
A6:E2 ECM
Engine Control Module (ECM) is on the left side of the engine. The ECM is a powerful computer that provides total electronic control of engine performance. The ECM uses data from engine performance that is gathered by several sensors. Then, the ECM uses this data to adjust the fuel delivery, injection pressure, and injection timing. The ECM contains programmed performance maps (software) to define horsepower, torque curves, and rpm. This software is commonly called the personality module.The engine does not have a replaceable personality module. The personality module is a permanent part of the ECM. The personality module for the engine can be reprogrammed by Cat® Electronic Technician (ET).ECM logs faults of engine performance. Also, the ECM can run several diagnostic tests automatically when the ECM is used with an electronic service tool such as the Cat ET.Priming Pump
Illustration 5 g06236499
(1) Electronic Fuel Priming PumpThe electric priming pump (1) forces the air that is in the fuel out of the system through the orifice on the regulator. Priming usually takes place after servicing the fuel system such as changing the fuel filter. This mode can also occur when the engine has not run for a long period. When the fuel system has air trapped in the fuel filters, lines, and other fuel system components, the engine could experience difficulty starting. The electric priming pump is turned on manually or the electric priming pump is turned on automatically to prime the system. The time for priming depends on the size of the fuel system. Nominal time of priming is about 30 seconds. This value varies by applications.Fuel Transfer Pump
Illustration 6 g06236645
(1) High-pressure fuel pump
(2) Fuel transfer pump
(3) Low-pressure fuel outlet
(4) Low-pressure fuel inletFuel transfer pump (2) is a pump that produces low pressure, high volume to pull fuel from the tank and through the primary fuel filter. Then, the pump sends the fuel through the secondary filter and the tertiary filter on the way to the high-pressure fuel pump. The high-pressure fuel pump feeds the injectors.High-pressure fuel pump