855708T25 Mercury IMPELLER

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Fuel filter assembly with a fuel priming pump
(1) Fuel priming pump
(2) Secondary fuel filter assembly
Fuel leaked or spilled onto hot surfaces or electrical components can cause a fire. Clean up fuel spills immediately.
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, "Cat Dealer Service Tool Catalog" or refer to Special Publication, PECJ0003, "Cat Shop Supplies and Tools Catalog" for tools and supplies suitable to collect and contain fluids on Cat products.Dispose of all fluids according to local regulations and mandates.
Do not allow dirt to enter the fuel system. Thoroughly clean the area around a fuel system component that will be disconnected. Fit a suitable cover over disconnected fuel system component.
Replacing the Fuel Filter Elements with the Engine Stopped
Stop the engine.
Turn off the start switch or disconnect the battery (starting motor) when maintenance is performed on fuel filters.
Shut off the fuel tank supply valve to the engine.
Unlock the fuel priming pump in order to relieve residual pressure in the fuel system.
Remove the used fuel filter. Use a cloth or use a container in order to catch excess fuel.
Clean the gasket sealing surface of the fuel filter base. Ensure that all of the old gasket is removed.
Apply clean diesel fuel to the new fuel filter gasket.
Do not fill the secondary fuel filter with fuel before installing. The fuel would not be filtered and could be contaminated. Contaminated fuel will cause accelerated wear to fuel system parts.
Install the new fuel filter. Tighten the fuel filter until the gasket contacts the base. Tighten the fuel filter by hand according to the instructions that are shown on the fuel filter. Do not overtighten the fuel filter. Note: DO NOT remove the plug in the fuel filter base in order to release the air from the fuel system during periodic service of the fuel filter. Periodic removal of the plug will result in increased wear of the threads in the fuel filter base.
Operate the fuel priming pump plunger until a strong resistance is felt and until the check valve clicks. This procedure will require considerable strokes. Lock the fuel priming pump.
Open the fuel tank supply valve.
Start the engine according to the normal operating procedures. Immediately increase the engine rpm between 1000 to 1200 rpm with no load. The engine will begin to misfire briefly until air from the fuel filter is purged. No damage to the engine will occur.
Do not crank the engine continuously for more than 30 seconds. Allow the starting motor to cool for two minutes before cranking the engine again.
If the engine stalls during the purging of the air, refer to the Operation and Maintenance Manual, "Fuel System - Prime" for more information. Replacing the Fuel Filter Elements During Engine Operation For Engines That Are Equipped With Duplex Fuel Filters
This filter contains pressurized fuel that can cause a fire hazard, which may result in bodily injury or death. Follow the instructions given in this Operation and Maintenance Manual and stop the engine if rapid air movement exists to blow the fuel.
Replacing the Main Fuel Filter
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Duplex fuel filters
Engines are shipped from the factory with the control valve in the MAIN RUN position.
(3) Fuel pressure gauge for the main fuel filter
(4) Plate that shows the position of the valve
(5) Fuel pressure gauge for the auxiliary fuel filter
(6) Control valve
(7) Auxiliary fuel filter
(8) Main fuel filter Use the following procedure in order to replace the main fuel filter while the engine is in operation.
Illustration 3 g01902917
Move the control valve to the LH FLOW - RH FILL position as marked on plate. The fuel pressure gauge for the main fuel filter should indicate full pressure. The fuel pressure gauge for the auxiliary fuel filter should indicate slight pressure. Five minutes may be required in order to fill the auxiliary fuel filter. The auxiliary fuel filter must become full of fuel.
Illustration 4 g01902918
Move the control valve to AUX RUN. The fuel pressure gauge for the auxiliary fuel filter should indicate full pressure. The fuel pressure gauge for the main fuel filter should indicate no pressure.
Remove the used main fuel filter. Use a cloth or use a container in order to catch excess fuel.
Clean the gasket sealing surface of the main fuel filter base. Ensure that all of the old gasket is removed.
Apply clean diesel fuel to the new main fuel filter gasket.
Install a new main fuel filter. Tighten the fuel filter until the gasket contacts the base. Tighten the fuel filter by hand according to the instructions that are shown on the fuel filter. Do not overtighten the fuel filter.