If the engine cranks, then there is nothing wrong with the EWS or keys.

If there is no fuel pressure at the rail when your ignition is switched on in position 2(KL15), and position 3(starter/KL50), and the starter cranks, then there is an issue with your fuel pump circuit.

if you have voltage present at the fuel pump while cranking, then MOST likely you have a faulty fuel pump.

However because of how the fuel pump relay is activated, overtime the fuel pump relay contacts can be burnt out, and it may close the contact when activated, so when you check for voltage, it will be present. During this scenario, you have full voltage, but high resistance in the circuit due to poor contacts in the relay. You will then have no amperage at the fuel pump. This situation usually occurs during cold weather in E46, and E53 BMWs. So when you bring your vehicle into a workshop or a garage where it is a lot warmer, you may not be able to duplicate the no start issue.