Dear Sirs:

Thank you very much for all your tips. I think the solution is on the way. I couldn´t read your post until today, but on friday y took away the box and put the tube inside the fuselage. The resut of this is that the engine worked much better on saturday and sunday, not asbolutly fine, but much better, so:

I'll chage the vent tube to a new possition as close as possible to the tank.
I'll have a look over all filters. There is one specific fuel filter whic can't be seen, but it's there.
I'll built a new box (without holes ) and I'll put it inside the fuselage.
I'll repport you

What a great and powerfull engine !!!

Regards,
Javier