COUPLING-PERMANENT 1242144 - Caterpillar

These engines have a pressure type fuel system. There is one injection pump and one injection nozzle for each cylinder. The injection pumps are in the pump housing (4) on the top front of the engine. The fuel injection nozzles are located in the fuel injection adapters. The fuel injection adapters are under the valve covers.The fuel transfer pump (16) pulls the fuel from the fuel tank (10) through the primary fuel filter (12). The fuel flows from the primary fuel filter (12) to the fuel priming pump (8) and through the main fuel filters (14). The fuel then flows to the manifold of the injection pump housing. The fuel in the manifold of the injection pump housing flows to the injection pumps. The injection pumps are in time with the engine. The injection pumps push fuel at a very high pressure to the injection valves (6).
Illustration 1 g00332354
Fuel flow schematic 3412C shown (1) Fuel inlet line for the injection pump housing. (2) Damper. (3) Restriction orifice. (4) Injection pump housing. (5) Fuel return line. (6) Injection valve. (7) Junction block. (8) Fuel priming pump. (9) Priming bypass valve. (10) Fuel tank. (11) Fuel supply line. (12) Primary fuel filter. (13) Fuel pressure gauge. (14) Main fuel filters. (15) Pressure relief valve. (16) Fuel transfer pump.A damper (2) is located on the inlet elbow of the fuel manifold (19). The damper (2) reduces the shock loads that are caused by the injection pumps. Some of the fuel in the fuel manifold is constantly sent through a restriction orifice (3). This removes air from the system. This restriction keeps the fuel pressure high. The restriction also controls the amount of fuel that goes back to the fuel tank through the fuel return line (5).
Illustration 2 g00332357
Location of the fuel system components 3412C shown (1) The fuel inlet line for the injection pump housing. (2) Damper. (3) Adapter with orifice. (5) Fuel return line. (11) Fuel supply line. (16) Fuel transfer pump. (17) The fuel outlet line from the transfer pump and the inlet line to the main filters. (18) The nut for a fuel injection line at the injection pump. (19) The fuel manifold across the injection pump housing. (20) Adapter through the valve cover base.The fuel priming pump (8) is used to fill the system with fuel. The fuel priming pump also removes air from the low pressure side of the fuel system. The low pressure side of the fuel system consist of the fuel filter, the fuel lines and components.
Illustration 3 g00332494
The location of the fuel system components 3412C shown (1) The fuel inlet line to the injection pump housing. (5) The fuel return line to the tank. (7) Junction block. (8) Fuel priming pump. (11) Fuel supply line. (14) Main fuel filters. (17) The fuel outlet line from the transfer pump and the inlet line to the main filters.The fuel transfer pump has a bypass valve and a check valve. The bypass valve controls the maximum pressure of the