The fuel pump and/or fuel pump relay can fail, causing the car to crank over but not start. Proper diagnoses will be necessary to confirm if the pump or relay is at fault.
Car Problem Reports
Mercedes-Benz 560SEL "No start" Caused by Failed Fuel Pump/Relay
Mercedes-Benz 560SEL Problem
Average Mileage: 87,500 mi (35,000 mi - 140,000 mi)