Recently my 07 +4 has failed to start first time when left for a few days. I can crank the engine for 5 seconds but she does not fire, however if I then switch off the ignition and try again it fires up instantly.

This problem only occurs when the car if left for around a week or longer.

I suspect there may be a tiny air leak somewhere in the fuel system so over a period of time the fuel in the pipes drains back into the tank. But then I would have thought the car would start but just take a few seconds longer than normal to pump the fuel through.

Maybe it is a feature of the ECU that if the car does not fire then you need an ignition cycle to try again.

Does anyone have any experience of this type of problem or any thoughts?

Thanks.