Diesel ignition

[Will]

I've been having a few problems with the ignition switch in my diesel Mercedes. What does the ignition switch in diesel cars do anyway? What happens when you turn the key to get one started, apart from engaging the starter motor, or to turn one off?

 

[Will]

Since a diesel engine doesn't use electricity to ignite the air/ fuel mixture, it is shut down by eliminating the fuel delivery to it. The fuel shut off valves on M-B diesels are vacuum actuated. When you turn the keyto start the engine, the fuel shut off valve is open. Key in off position closes the valve. Emergency shut down lever inside engine compartment is mechanical.