NMWR-9-2815-220 Overhaul Manual for M60 M88 Engine AVDS-1790-2CA, AVDS-1790-2DA, AVDS-1790-2DR Download
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NMWR 9-2815-220 EQUIPMENT DESCRIPTION AND DATA—Continued 0002 00 LOCATION AND DESCRIPTION OF MAJOR COMPONENTS - CONTINUED (3) Fuel Injection Metering Pump. The fuel injection metering pump is located in the “V” of the engine between the fan drive housings, and supplies fuel under high pressure to each cylinder. The pump is driven at engine speed from the fan drive housing located at the rear of the engine. A fuel injection pump advance assembly (9, Figure 1) is incorporated in the accessory drive housing to automatically provide a gradual degree advance of injection timing during the engine speed range from idle to 1800 rpm. (4) Fuel Injector Nozzles and Tubes. Twelve fuel injector nozzles (Figures 3 and 4), one per cylinder, are used to inject fuel into the combustion chambers. Twelve fuel injector tubes of equal length carry the fuel from the fuel injection pump to the nozzles. The nozzles on each cylinder bank are interconnected by fuel return lines to provide a path for the return of excess fuel. (5) Fuel Purge System. A manually operated purge pump is provided in the vehicle operator’s compartment and is used to clear the engine main fuel system and flame heater system of air, and fill them with fuel. Most of the purged air is removed through bleeder valves located in the top of the primary fuel filter and the fuel/water separator filter. The rest of the air is forced through the main fuel tubes into the fuel return lines and on to the vehicle fuel tanks. Water is removed from the system by a constant bleed orifice in the primary fuel filter and an automatic water drain in the fuel/water separator filter. (6) Fuel Filters. The replaceable element type primary fuel filter is mounted on the left front of the engine and is equipped with a constant bleed orifice and drain line which constantly removes a metered amount of fuel and returns it to the main fuel tank through the fuel injector nozzle drain lines. This continuous drain, from the bottom of the filter, removes water in the free state that has been filtered from the fuel by the primary fuel filter element. The replaceable element fuel/water separator type filter is mounted on the left front of the engine. Fuel from the vehicle fuel tank passes through the primary filter before entering the engine fuel pump. The pump delivers fuel to the fuel water separator filter and on to the fuel injection pump. Excess fuel provides pump cooling as it flows through the fuel injection pump hydraulic heads and is returned to the fuel tanks (Figures 3 and 4). The fuel water separator filter unit has three replaceable elements and contains a chamber for collecting water. The two outer elements are coalescer elements and will remove emulsified water that has passed through the primary filter. The center element is a fuel filter element. The water removed from the fuel is automatically drained from the filter housing. Two water sensing probes are located in the filter housing. When the water level reaches the upper probe, an electrical circuit is completed, a solenoid valve opens and allows the water to drain. The valve closes when the water level reaches the lower probe. A drain cock is installed so the fuel/water separator may be drained manually. The unit provides moisture-free and uncontaminated fuel to the injection pump. Both the primary filter and the fuel/water separator filter incorporate top mounted bleeder valves to assist in the removal of air from the fuel system. (7) Fuel Cutoff Solenoid. An electrically operated fuel cutoff solenoid is mounted in the fuel injection pump. The solenoid is normally open. A switch in the vehicle driver’s compartment actuates the circuit to close the solenoid. Closing the solenoid cuts off fuel delivery from the fuel injection pump and stops the engine. A manually operated override shutoff is provided to permit stopping the engine in the event of an electrical failure. (8) Fuel Return Backflow Valve. A fuel return backflow valve (Figures 3 and 4) is installed between the fuel injection pump fuel return outlet and the fuel return hose assembly. The valve prevents fuel flowing back to the injection pump when the fuel supply is closed. 0002 00-10 Change 1