TM-9-2815-200-35 Maintenance Manual for AVDS-1790-2M AVDS-1790-2A and AVDS-1790-2AM Engines Download
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e. Fuel Filters (figs. 1-3 and 1-6). The replaceable element type primary fuel filter is mounted on the right front of the engine and contains a fuel drain or purging line. The replaceable element type secondary fuel filter, or the water / separator type filter, is mounted on the left front of the engine. Each filter has a drain or purging line connected to separate drain cocks mounted on a common bracket on top of the engine. Each drain cock is fitted with a flexible hose for dumping drainage from the filters. Fuel from the vehicle fuel tank passes through the primary filter before entering the engine fuel pump. The pump delivers fuel to the secondary filter, or the fuel / water separator filter on late engines and on to the fuel injection pump. Excess fuel bypasses the fuel injection pump and is returned to the fuel tanks (fig. 1- 11). The fuel/ water separator filter unit has three replaceable elements, and contains a chamber for collecting water. The unit provides moisture-free and uncontaminated fuel to the injection pump. f. 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 com- partment actuates the ciruit to close the solenoid. Closing the solenoid cuts off fuel delivery from the fuel injection pump and stops the engine. g. Fuel Return Check Valve. A fuel return check valve (fig. 1-11) 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. 1-19. Manifold Air Induction and Heater System a. Turbosupercharger Assemblies. Exhaust gas driven turbosupercharger assemblies (figs. 1- 1, 1-2, and 1-4), one for each bank of cylinders, are mounted on each side of the engine, at the rear. The turbosuperchargers increase the pressure of the intake air, thereby delivering a higher density air to the cylinders as compared with a non-supercharged engine. This higher density air, with a proper fuel flow, increases engine power. 1-15