3T5Q87304-3 Nissan LOWER UNIT ASSEMBLY "UL"

Illustration 1 g00712565
Fuel system schematic (A) Fuel priming pump (if equipped) (1) Screen (if equipped) (2) Inlet check valve (3) Fuel transfer pump that is integral with the governor (4) Outlet check valve (5) Fuel filter (6) Cylinder head (7) Pressure regulating orifice (8) Check valve (9) Primary fuel filter (if equipped) (10) Fuel tankFuel from fuel tank (10) is pulled through an in-line screen (1) by fuel transfer pump (3). The fuel transfer pump is integral with the governor. Fuel is sent from the fuel transfer pump through fuel filter (5) to a drilled passage in the cylinder head (6). The drilled passage in the cylinder head intersects a gallery around each unit injector in order to provide a continuous flow of fuel to all injectors. Unused fuel exits the cylinder head and passes through pressure regulating orifice (7) and check valve (8) before returning to fuel tank (10). Pressure regulating orifice (7) is located in the fuel return tube assembly. This pressure regulating orifice ensures adequate fuel gallery pressure for low idle fuel flows. Check valve (8) prevents fuel from leaving the cylinder head fuel gallery during engine shutdown.When there is air on the inlet side of the fuel system, fuel priming pump (A) (if equipped) may be used in order to fill the fuel filter and the fuel gallery that is in the cylinder head. This is performed before the engine is started. When the priming pump is used, check valves that are located in the fuel priming pump control the movement of the fuel. The fuel is forced through the low pressure side of the fuel system. This removes air from the fuel lines and components back into the fuel tank.
Illustration 2 g00712706
Lines group for the fuel filter (3) Fuel transfer pump that is integral with the governor (5) Fuel filter (6) Cylinder head (11) Fuel outlet port to the fuel tank (12) Fuel inlet port to the fuel transfer pump (13) Fuel filter base (14) Pressure tap for filtered fuel (15) Tube assembly from the fuel filter base to the fuel gallery in the cylinder head (16) Tube assembly from the transfer pump to the fuel filter base
Illustration 3 g00712708
Lines group for the fuel filter (view (A-A) ) (1) Screen (if equipped) (6) Cylinder head (7) Pressure regulating orifice (8) Check valve (11) Fuel outlet port to the fuel tank (12) Fuel inlet port to the fuel transfer pump (16) Tube assembly from the transfer pump to the fuel filter base (17) Tube assembly from the fuel passage in the cylinder head to the fuel tankType II Fuel System
Illustration 4 g00690661
Fuel system schematic (A) Fuel priming pump (if equipped) (1) Screen (if equipped) (2) Inlet check valve (3) Fuel transfer pump that is integral with the governor (4) Outlet check valve (5) Fuel filter (6) Cylinder head (7) Pressure regulating orifice (8) Check valve (9) Primary fuel filter (if equipped) (10) Pressure relief valve (11) Fuel tankFuel from fuel tank (11) is pulled through an in-line screen (1) by fuel transfer pump (3). The fuel transfer pump is integral with the governor. Fuel is sent from the fuel transfer pump through the pressure relief valve (10). The pressure relief valve is closed in normal operation. Fuel will enter through fuel filter (9) to a drilled passage in the cylinder head (6). Once the pressure of the fuel is greater than the desired range then the pressure relief valve will open. This will allow the fuel to return to the tank. The drilled passage in the cylinder head intersects a gallery around each unit injector in order to provide a continuous flow of fuel to all injectors.When there is air on the inlet side of the fuel system, fuel priming pump (A) (if equipped) may be used in order to fill the fuel filter and the fuel gallery that is in the cylinder head. This is performed before the engine is started. When the priming pump is used, check valves that are located in the fuel priming pump control the movement of the fuel. The fuel is forced through the low pressure side of the fuel system. This removes air from the fuel lines and components back into the fuel tank.
Illustration 5 g00690672
Lines group for the fuel filter (3) Fuel transfer pump that is integral with the governor (5) Fuel filter (6) Cylinder head (10) Pressure relief valve (12) Fuel outlet port to the fuel tank (13) Fuel inlet port to the fuel transfer pump (14) Fuel filter base (15) Pressure tap for filtered fuel (16) Tube assembly from the fuel filter base to the fuel gallery in the cylinder head (17) Tube assembly from the transfer pump to the fuel filter base
Illustration 6 g00690675
Lines group for the fuel filter (view (A-A) ) (1) Screen (if equipped) (6) Cylinder head (7) Pressure regulating orifice (8) Check valve (10) Pressure relief valve (12) Fuel outlet port to the fuel tank (13) Fuel inlet port to the fuel transfer pump (17) Tube assembly from the transfer pump to the fuel filter base (18) Tube assembly from the fuel passage in the cylinder head to the fuel tankFuel Heater And Water Separator (If Equipped)
Illustration 7 g00839038
Fuel heater and water separator (1) Fuel filter (2) Heater (3) Drain valve (water) (4) Temperature sensorSome engines have a fuel heater and a water separator together. The fuel heater is controlled by a thermostat that is located in the base of the unit. The thermostat is preset in order to turn on the heater when the fuel temperature is below 2 °C (36 °F). The fuel heater will turn off when the fuel temperature is 7 °C (45 °F).Water that has been separated from the fuel can be drained from the unit by lifting up on drain valve (3) .Fuel Transfer