Okay Denny, I stand corrected. Yes, Jon deserves the credit for my solution with his carburetor troubleshooting information. Thank you Jon!
Any way, it took me a few days to get back out in the garage and get after the problem and post the update. Let me set the stage for you. The gas tank hasn't had but few gallons of gas in it. I just completed the installation of the 16 gallon gas tank kit last winter. On several occasions I noticed the 'swish' sound when I removed the gas cap, which did seem odd to me, assuming that I had a vented gas cap. So when I took the truck for a drive, about a mile, it was probably 75 to 80 degrees outside. I'm sure that there wasn't much more than a gallon of gas in the tank. When I stopped the truck it was running rough and the engine stalled. So I popped the hood and saw that gas had leaked from the throttle shaft ends and the intake and exhaust manifolds were soaked too. That's when I turned to the knowledge base here on the 'bolt'.
The gas cap had a spring type one-way relief valve in it which should have alleviated a positive pressure condition. However, it must not have worked correctly. I too believe that if a vacuum was created, the truck would not run for very long. The over pressure issue does not seem to be a problem now. Perhaps the little amount of run time I've had with the truck and this gas tank configuration speak to the vacuum issue not fully presenting itself?
So, that's my story and I'm sticking to it. Once again, I am amazed and most grateful for the knowledge and expertise demonstrated here on the Stovebolt.
Thanks,
