OK, the C280 will crank, then start but immediately die. Any ideas?

 

Hello, You may be experiencing a ignition switch failure or an electrical issue related to it. All modern cars have circuitry that shuts the fuel pump off in a crash, or roll over. Your car probably has a fuel pump relay with a number of wires that must provide a signal to hold it in. Usually when you turn the key to crank the engine there is a signal from the start circuit that holds the relay in for about 5 seconds. When you release the key to the run position if you have both oil pressure and power from the run circuit the fuel pump continues to run. Ignition switches wear out and fail just like yours. Oil pressure switches sometimes as well. Those are 2 places to look. There are others , but without a wiring diagram specific to your year and model help will be difficult Good luck Allan