Mercedes e270 cdi, cranks but will not start.?

It's definitely a fuel delivery issue. Could be injectors or the pumps . I am not sure about your particular engine but on a modern diesel there should be 2 pumps. One pump is the low pressure pump that brings fuel from the tank to the engine. That's a simple electric pump. The other pump is the high pressure pump. This pump is responsible for pulsing fuel into the combustion chambers at very high pressures. That pump is usually mechanical, not electric, meaning it's driven off of the engine itself. It's possible this high pressure pump has an issue. That is where I would bet the problem is.