MMMM sorry if I did not pick it up in the thread but have you done as Mike (#9) suggested. Sounds to me like rust has slowly been building in the inner wall of your gas cap. When the cars dies it will take 10-20 minutes and then it starts. That time span is what it takes for the air to travel back into the tank. As Mike mentioned when it dies the first thing is SLOWLY remove the gas cap and listen for the swoosh. Carefully blow the cap with an air nozzle. Rust particles will fly all over hell. Don't ask me how I know.
Steve,rubber tip needle valves are prone to this issue. My neighbors ford 600 tractor is having this intermittent fuel starvation problem. With a jewelers loop I found the hole in the seat to be very poorly drilled and was acting as teeth into the rubber tip. With seat out and barely any pressure put on to seat the needle, I could not get it to 'release' with out physically pulling it out. So we put in an old seat that I very lightly 'honed' with a dremel stone to slightly chamfer the 90* hole in the seat, so far so good. If the problem arises again, I'm going to clip the needle to the float, this will for sure cure the issue on the tip sticking to the seat.
Another thing that I seen that clogs vents in gas cap is this wonderful "gasoline". After the gas gets 3 months old or so it forms a Permatex gasket sealer type of goo and as the gas sloshes around in the tank and out the vents and after time goes by the "goo" dries up, gets hard and seals up the vents in the cap.
I have seen many carbs with jets completely closed up with the crap! Stuff is very hard to remove without soaking in lacquer thinner.
Another reason to not leave the gas in tank if you store the car over the winter.
It also helps to remove all of the fuel from the carb and remove the fuel line incase the shut off valve is leaking so fuel does not sit inside the carb all winter.
I drive the cars year round so it is not a big problem for me.
I do not know if it is the Ethanol or some other junk that they put in there that causes it to get all gooey. "Better gasoline through science".
This kind of thing seems to happen whenever "management" gets involved in the making of a product instead of the people that actually know how it works.
I cannot determine if my after market repro gas cap has a blocked vent.
The tiny metal hole on the inside of the cap seems to simply reveal the red colored hard paper gasket underneath it. Is there an easy way to check if the vent is working? Thanks. Does anyone make a quality gas cap or are they all cheap repros?