Hi there, i have had this same problem with my 4.4i. I havent taken to the dealer as of yet due to being really busy, so my X5 sits some days due to this starting problem. I have realized that when i take out the interior light fuse and plug it in again, and then wait 10-20 seconds, the car starts up. Can someone figure this out so i dont get hammered at the dealer.

Hello, i had the same issue, it cranks but just wont start, i towed it to the garage and the said it was the fuel pump, the said they replaced it for $600, and it worked for 4 weeks, yesterday i had the same problem in the morning, to my surprise i tried to start it in the evenig and it worked, but on the road after 2500 rpms it kind of lost power and got shaky, im thinking its dirt in the fuel or injectors, or fuel filter need to be replaced. The strangest is that right now its working just fine. Any thoughts?.....

Hi, I had the fuel pump replaced 1 year ago and it has been fine since then. I never had any problems whilst driving like you described. I was told fungi can build up in diesel tanks and can cause the problems you are experiencing. If yours is a diesel try a treatment for your fuel tank, i'm pretty sure Nissan sell them, thats whats the head mechanic at my bmw dealer told me. Good luck with it all