My mates audi a3 140 tdi doesn't start sometimes, he notices that if not used for a day that in the morning it doesn't start. It's been to the garage twice and Ł500 spent and it still does it. He gets it to start using easy start but said he had to have the accelerator fully down. So it is a fuelling issue, I was thinking maybe a tiny fuel leak then pressure dropping, but I've told him about priming it a few times before starting, yet it still didnt start without easy start. Anything obvious?