I thought about vapor lock, but I cut the line between the tank and the pump (fuel gravity fed out of the tank freely...mostly down my arm and into my face), I broke the connection at the pump and blew air backwards through the fuel line toward the tank (tasted nasty!), and I removed the galss bowl off the filter assembly. I could blow air through the line, but not as freely as I would have thought possible through a 5/16" line. I have a glass bowl filter between the pump and the carb. I could see the pump "blowing" against the filter element, but no gas. Fuel line is coming off today to see if there is something in the line. One thing that is probably worth mentioning...this fuel tank is not in the cab. It is a 50 gal aluminum tank mounted in the bed underneath the tool box. I suspect that there is a partial blockage in the fuel line not allowing enough gas to be delivered to the pump under load.
