...temperature, any clues please?
it only does it at normal temp. the engine just turns over as if there's no petrol or electric contact at all. no carb, so its not a flooded problem.

Although car your does not have a carb it does have a choke in the form of a sensor that sends a signal to the ECU (computer)
Its probably a fault with the sensor,its sending an incorrect reading to the ECU and therefore overfueling.

totally agree with jr,a very common problem. nice one jr keeping it real for us merc technicians.

have your battery checked