The International Cessna^® 170 Association

canav8 wrote:Your cap vent is inoperative. Repair or replace it. Also check to make sure you have pliable gaskets on the cap. Fuel problems are generally associated with rubber that has deteriorated in the valve and the seals.

No. The cap vent is designed as a check-valve. It will contain pressure (except for the gooseneck which relieves accumulated pressure), but the cap will allow atmosphere to enter to tank.
It sounds as if his gooseneck is inop or plugged. (mud daubers? wasps? etc.)

gahorn wrote:

canav8 wrote:Your cap vent is inoperative. Repair or replace it. Also check to make sure you have pliable gaskets on the cap. Fuel problems are generally associated with rubber that has deteriorated in the valve and the seals.

No. The cap vent is designed as a check-valve. It will contain pressure (except for the gooseneck which relieves accumulated pressure), but the cap will allow atmosphere to enter to tank.
It sounds as if his gooseneck is inop or plugged. (mud daubers? wasps? etc.)

You probably want to rethink that George.

What am I missing, Doug?
The vent on the caps is a one-way vent. It allows atmosphere IN to the tank.

(But if you're referring to the issue of fuel pressure being held in the system, I agree that his gooseneck must be plugged.)

So I figured it out and it is kind of embarrassing. I checked the vent and it was fine, after standing back and looking at the plane my friend noticed the plane was on a slight angle. So by leaving the fuel selector on both and having the tanks full, well there you go....duh..thats it!

There should still be no pressure held within the tanks.