Seat ibiza 1.4 petrol, 2009, does not start as if in the sun

Hello. I have a problem that with his Ibiza 6j from 2009 1.4 16V gasoline. When he stays in the sun for a long time he has serious problems with tanning. It will only start for 5 - 6 times and when it's cold, it starts up from behind. I've been to a few mechanics and everyone decomposes hands. The computer was also plugged in and nothing. Do you have any ideas?

Hello, what about the mechanics' knowledge has ended with checking the error codes? And what about the parameters in real time? Some data such as what temperature the controller sees, the shaft position sensor ...

As a rule, checking for errors ends. There are no errors, the car is operational he. The mechanics these days.

Today's mechanics rely on such a well-known forum as ELECTRODA, if they do not find an answer, it can not be done and if there are no errors, the car is in working order haha, you can go 100 PLN you should. to determine something because we have too little data.

Temperature and lambda okay according to the second mechanic.

How to stand in the sun is a problem, and if you take a drive and it's hot is also a problem with firing?

Not then not.

Fuel tank vent valve, underneath the air cleaner housing. The topic has already been described on this forum, but if the hint was helpful, it's hard to write.

This valve needs to be replaced and you think it will be fine?

Added after 6 [minutes]:

I'll try to replace it. Thanks for all the hints.

It is very easy to check if the valve is leaky, you can, for example, plug the vent line for a test

Oki. Thanks again.