4921A 1 Mercury GEAR HOUSING ASSEMBLY

The fuel in the electronic control module and in the hose assemblies connected to the module may be under high pressure. When the hose assemblies connected to the module are disconnected, the pressure will be released.Fuel under high pressure can penetrate the body causing personal injury.To release the pressure, slowly loosen the hose assembly.
Personal injury or death can result from a fire.Fuel leaked or spilled onto hot surfaces or electrical components can cause a fire.Clean up all leaked or spilled fuel. Do not smoke while working on the fuel system.Turn the disconnect switch OFF or disconnect the battery when changing fuel filters.
Care must be taken to ensure that fluids are contained during performance of inspection, maintenance, testing, adjusting and repair of the product. Be prepared to collect the fluid with suitable containers before opening any compartment or disassembling any component containing fluids.Refer to Special Publication, NENG2500, "Caterpillar Tools and Shop Products Guide" for tools and supplies suitable to collect and contain fluids on Caterpillar products.Dispose of all fluids according to local regulations and mandates.
Note: Install caps and plugs on all openings in order to prevent dirt or debris from entering the system. Cleanliness is an important factor. Before the removal procedure, the exterior of the component should be thoroughly cleaned. This will prevent dirt from entering the internal mechanism.
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Turn ball valve (1) that is located on the fuel tank to the OFF position.
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Disconnect fuel hose assembly (2) and fuel hose assembly (4) from engine electronic control (3) .
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Loosen two socket head screws (6). Disconnect two wire harnesses (5) from the engine electronic control. Position the wire harnesses away from the engine electronic control.
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Remove four bolts (8), ground strap (7), the mounts, the spacers, and the washers that hold engine electronic control (3) in position. Remove the engine electronic control from the engine.Installation Procedure
Note: Check all of the O-ring seals and the components for wear or for damage. Replace the components, if necessary. Lubricate all of the O-ring seals lightly with the lubricant that is being sealed. Clean all of the components with a cloth that is free of loose material (lint). Note: If a new engine electronic control will be installed, refer to Troubleshooting 3500B Engines for Caterpillar Built Machines, SENR1128, "Replacing the Electronic Control Module (ECM) With a New ECM".Note: If a used engine electronic control will be installed, refer to Troubleshooting 3500B Engines for Caterpillar Built Machines, SENR1128, "Replacing the Electronic Control Module (ECM) With a Used ECM".
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Position engine electronic control (3) on the engine, as shown. Install four bolts (8), ground strap (7), the mounts, the spacers, and the washers that hold the engine electronic control in position.
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Connect two wire harnesses (5) to the engine electronic control. Tighten two socket head screws (6) that hold the wire harnesses in position.
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Connect fuel hose assembly (2) and fuel hose assembly (4) to engine electronic control (3) .
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Turn ball valve (1) that is located on the fuel tank to the ON position.
Prime the fuel system. Refer to Operation and Maintenance Manual, "Fuel System - Prime".