I had a similar problem and the car would take two or more tries to start after warm up and leaving the car for 1/2 hour or so. Turned out to be leaky/bad check valves in the in-tank fuel pump return lines.

Worth the check.

 

So I did Johnspeed's car- pressure test form the upper Y pipe for now, and found 3 boost leaks... the FPR vacuum line was completely OFF... the F hose clamp was loose and leaking, and one more vacuum line to the left of the IPD plenum was leaking... same symptoms as the OP... I will have a complete video of everything I did when its all done...
here is the initial test... I suggest you guys invest in some boost leak testers and some logging capabilities... check the cars and the tune...
markski

 

First, Anikzad, I missed your post, which was the correct advise. So here's the story.

After many many months of warm start problems and several mechanics trying unsuccessfully to diagnose the problem, I went on a hunch and it turned out to be right.

My problem appeared initially to be a heat soaked or warm difficult starting problem. If the car was cold it started right up. If warm and turned off and restarted immediately it started right up. If warm and it sat for +10 minutes, it would hard start.

One day, I didn't start the cold engine, but simply turned the key to on to see how much gas I had in the tank thereby pressurizing the fuel system. 10 minutes later I tried to start it and got the hard start (long crank).

As always, the smell of fuel was present on a long crank.

What I guessed was that the fuel pressure remained in the lines well after the engine was turned off and it was leaking into the cylinders and flooding the engine causing the hot start.

What I replaced is the fuel return check-valve, which I confirmed was clogged, with a new one from ebay for <$10 and the problem immediately went away. Replacing it requires heating the clear fuel tubes to soften them enough to get them off of the press fittings and then again to get them back on.

Who knew?

So I am posting here just in case this happens to others. The <$10 part from ebay was my option as I could not find the original part anywhere and Porsche only sells the fuel pump complete for +$700 and replacing the entire pump for such a small part failure seemed like a waste of good money.

 

Joe,
First I am glad you found your problem. Second, Just because some of us don't post a lot does not mean we don't get ourselves into trouble :-)

My issue was resolved by Betim at BBi, so I learned a valuable lesson (vs. shipping the car to EVOMS once and they did not address the problem).

In any event, This I think is valuable thread for others to reference as more and more will face this issue as the cars are getting older.

 

All,

So someone correctly pointed out that the check valve I replaced goes to the injectors not from the injectors, which kind of blows my flooding theory, but the fact remains that this check valve was faulty and replacing it completely and immediately solved the problem. Not sure how the clogged check valve manifested the problem, but replacing it fixed it. Better to be lucky than smart

 

Joe 731-

what size check valve did you get? i am having the same issue but dont know type, size etc. any help would be greatly appreciated.

 

5/16 or 8mm, I got one from upr on ebay

 

http://www.ebay.com/itm/UPR-8MM-Non-...05c293&vxp=mtr

This is what i found is this correct. Thanks for all your
Help...

 

Yes, that is the one I am using