891868 Mercruiser O-RING

Fuel Tank
Open the fuel tank drain valve to drain water and sediment from the fuel tank. To minimize water contamination, fill the fuel tank in the late afternoon if possible. As the fuel is consumed, air with some humidity must replace the fuel in the tank. By filling the tank in the late afternoon, this humid air is expelled before the moisture can condense on the cool inside walls of the fuel tank.Fuel Filters
Draining Water And Sediment
1. Close the fuel supply valve if the fuel tank is located above the level of the fuel filters.2. Remove the drain plug from one cover of the fuel filter housing. Drain water and sediment from the filter housing.
REMOVING FILTER HOUSING DRAIN PLUG3. Install the drain plug.4. Remove the drain plug from the other cover of the fuel filter housing.5. Drain water and sediment from that end.6. Install the drain plugs and vent plug.7. Prime the fuel system.Priming The Fuel System
1. Open the fuel supply line valve.2. Move the governor control lever to the shut-off position.3. Turn the pump handle knob counterclockwise; release the lock plate from the retainer on the fuel priming pump.4. Operate the fuel priming pump until the air in the fuel system has been pumped through the fuel return line to the fuel tank.If desired, the fuel return line connection may be loosened. When a solid stream of fuel flows from the connection, air has been expelled and the connection can be tightened.
OPERATING THE PRIMING PUMP5. Secure the pump handle: Turn the lock plate vertically, turn the pump handle knob clockwise until the lock plate contacts the plate retainer.6. Start the engine. If the engine misfires or smokes, loosen a fuel injection line nut, and allow the fuel to flow until free of air bubbles. Tighten the line nut; open the next line nut and continue venting each successive line.
LOOSENING FUEL LINE NUT AT THE NOZZLEChecking Fuel Pressure Gauge
With engine running, the fuel pressure gauge should register in the NORMAL range. If the gauge registers in the OUT range, service the fuel filter elements.Cleaning Primary Filter Element
1. Stop the engine.2. Close the diesel fuel supply line valve.3. Loosen the nut on the cover and remove the case.
REMOVING PRIMARY FUEL FILTER4. Remove the filter element. Clean the element and case in kerosene or diesel fuel.5. Inspect and install the upper and lower cover gaskets. Install new gaskets if necessary.6. Install the cleaned filter element and case.7. Open fuel supply line valve.8. Prime the fuel system.Installing Final Fuel Filter Elements
If your engine is equipped with a standard fuel filter system, read the following instructions. If your engine is equipped so as to permit changing the fuel filter elements while the engine is operating, read the topic, "DUPLEX FUEL FILTER SYSTEM".1. Close the fuel supply line valve.2. Remove the drain plug in each cover. Drain the fuel filter housing.
DRAIN PLUG3. Remove both end covers.
REMOVING FILTER COVER4. Push the used filter elements from left to right through the filter housing.
REMOVING USED FILTER ELEMENTS5. Wipe sediment from inside the filter housing; use a clean cloth.6. Inspect the cover gaskets. Install new gaskets if necessary.7. Install the right cover. Install new filter elements.
INSTALLING NEW FILTER ELEMENTS8. Install the left cover.9. Install the drain plugs in the covers.10. Open the fuel supply line valve.11. Prime the fuel system.Duplex Fuel Filter System
During normal engine operation, the selector lever should be positioned in the "MAIN FILTER RUN-AUX. OFF" position. The fuel will then be filtered by the main filter elements located in the right hand side of the fuel filter housing. Two filter elements, located in the left hand side of the fuel filter housing, are auxiliary filter elements. When standing at the flywheel and looking forward, the right hand side is to the right, and the left hand side is to the left.When the fuel pressure gauge indicates minimum acceptable pressure (20 psi), the main fuel filter elements must be changed. The fuel must be filtered by the two auxiliary filter elements while the main filter elements are being changed.1. Move the selector lever to the AUX. VENT-MAIN RUN position.Any air in the auxiliary filter housing will be vented back to the fuel tank while the main fuel filters will continue to filter the diesel fuel.
"AUX. VENT-MAIN RUN" POSITION2. After air bubbles are no longer