Mercedes, diagnostics of the high-pressure fuel pump of the petrol engine in Hevel Eilot

Mercedes, diagnostics of the high-pressure fuel pump of the petrol engine in Hevel Eilot.
When does a high pressure fuel pump (HPFP) of the petrol engine need diagnostics? The engine does not pick up the required speed, the fuel consumption has increased for some unknown reason, you have difficulty starting your car, the engine fails, the vehicle's exhaust is more concentrated and has an unusual odor, there is some extraneous noise in the pump or a fuel leakage, fuel is not supplied to the injectors. All these are signs of a malfunction of the high pressure fuel pump that must be checked within the framework of diagnostics: integrity of the fuel injection valves; a fuel supply starting point; pump performance in various modes; functionality of plunger sections; the functionality of the intake and exhaust valves; serviceability of electronic units.