Mercedes-Benz CLK500 no start issue with fuel pump and ignition key left overnight on Mercedes-Benz CLK500

Some Mercedes-Benz CLK500 owners report experiencing no-start issues potentially linked to the fuel pump, especially after leaving the ignition key on overnight. These owners note that a malfunctioning fuel pump can result in inadequate fuel flow to the engine, making it difficult to start the vehicle. Additionally, they emphasize the importance of checking the fuel pump relay, as the absence of a humming sound when turning the ignition may indicate a fuel pump problem. The fuel pump's location inside the fuel tank can complicate repairs, particularly if damage occurred after a collision. Owners also highlight the need to inspect electrical components, as issues with the ECM, ignition switch, or shift interlock system may contribute to the no-start condition. Furthermore, some owners recommend checking the fuel system pressure at the Schrader valve, which should be between 53-61 psi, and monitoring the fuel pump's current draw, ideally between 4 and 9 amps, to diagnose fuel delivery issues effectively.