Short description
When the engine is started, the fuel pump starts to work and draws fuel from a reservoir located inside the fuel tank. The fuel is drawn through a filter in the engine bay to the engine's fuel pump.
The return fuel, i.e. the fuel that is not used, flows back to the fuel tank where it passes a negative ejector located in the fuel tank. In turn, the ejector fills the reservoir from which the diesel pump draws fuel. Put simply, an ejector is a cylinder with three openings, one at each end and one in the wall of the cylinder. When fuel flows through the cylinder (in at one end and out the other), negative pressure is created at the hole in the cylinder wall. The negative pressure is used to draw the fuel from the fuel tank and keep the reservoir full.
The reservoir is located in the fuel tank. The reservoir is to ensure that the pump can draw fuel irrespective of the angle of the car.
The fuel filter is located by the engine bay. Its task is to separate impurities and water from the fuel so that the system is not damaged.