Jetta TDI 2014 will only start at 2nd try

[Marchuot]

Jetta will start only at second try
Vw dealer change Fuel filter
Fuel tank pump
High pressure fuel pump
And back flow fuel valve
Seams like pressure is lost in fuel line after short time
VW cannot resolve problem, car still on warranty, all parts paid by VW!

Any clues?

 

[Lug_Nut]

Try the second start before the first attempt?
Does it matter how long the engine cranks on the first attempt? If you run the starter for 20 seconds the engine doesn't run on its own. If you run the starter for 2 seconds the engine doesn't run on its own. What about 0.2 seconds of starter operation, then key off and back on to start, the engine starts and runs immediately?
Once running on its own, and the engine is then shut off, what is the re-start situation? Starts immediately? What about after being shut off for 5 minutes, or 15 minutes, or an hour? Is it always a no-run condition on the first re-start attempt, and always starts and runs on the second?

I have a pull start lawn mower with a "one pull start" guarantee decal on it. I asked the factory authorized service shop about that. Their reply was that the first pull on the cord was not promised to be the one pull that finally started the mower. A more accurate decal would have been "last pull start".