Note: A leak in the fuel injector valves can cause difficulties when starting a hot engine. Damage to the injectors can cause the diesel effect, when the engine continues to run with the ignition off.
1. Start the engine at idle speed.
2. Using a stethoscope, check that each individual injector is functioning properly - the presence of clicks indicates that the valves are opening and closing properly.
Note: If you don't have a stethoscope handy, you can check by touch using a screwdriver or your finger.
3. If unusual sounds are detected, as well as in the complete absence of such, it is necessary to ensure that the supply voltage to the injectors is working properly, measure the resistance of the injectors and check them for leaks.
Material borrowed from an online resource: mercedesman.ru