Originally Posted by scottmillhouse
Drill the vent hole anyway in the cap. You need it with a full tank on takeoff. Obviously fuel blocks the new vent and fuel pressure goes down which is kind of scary on a take off. It will stabilize when you level out and burn fuel. There is no problem with the cap vented too.
First time I've heard of this - I've never seen ithappen in my -12 ...
Port Orange, Fl
RV-12 N121TK ELSA #120845; first flight 06/10/2015
RV-12 N918EN ELSA #120995 Eagles Nest Project; ready for engine & avionics