]My 2006 XC90 have been acting weird for some time now, so it would not start, assumed it was battery got told it had a parasitic draw. We took it in they found nothing. Started keeping it on trickle charge over night which helped but then not even that worked it started cranking sluggish and if you turned it on it was a 50/50 if you would get it working again.
we have disconnected the battery while it’s running so it’s not the alternator either
I was thinking maybe fuel filter? There is no codes so it’s really hard to tell..
I tried attaching a video of it but it wont let me.
Here is a youtube link of it.

 

Since your vid shows the car cranking albeit a bit slowly, I'd look at a few things: Battery voltage (car off, engine running). An 80% charged battery will be in the 12.6V range. When it goes down say below 12.2 it may not have enough to crank over/start. Next is to check cables and battery terminals. Look for signs of bubbles / melting on the heavy cables - that's a sign of resistance (ie corrosion). Check/clean battery posts, connection on the big lead to the starter and the ground strap at the chassis. If cleaning up the battery terminals etc doesn't help, next thing I'd suspect is a starter or a starter cable issue.

 

So its like a 50/50 if the car starts or not like sometimes you can have it like that for minutes without it starting we have checked all cables and terminals etc and found nothing which is why we were trying to find guesses outside of the battery I will have them double check everything tonight again though! Thank you for your suggestions!

 

Side note here is a video of the car when it is not starting