The tank is the same one that's been in the truck since I bought it in 1985. I thought about a pressure or vacuum problem with the tank, but the tank makes no noise when I take the cap off. Had that same cap on there for 30 years with no issues. I have the old style fuel pump with the glass bowl and filter screen. Also have another fuel filter in line right before carb. No junk in either. Thanks for the advice about new pumps - not surprised. I just had to replace a water pump and they're all made in China now. It's holding up for now, but don't know how long it will last. Darned shame. I've got some old US made water pumps on the shelf that rattle - next time I may just have one of them rebuilt. No spare US made fuel pumps, though.
I think I'm going to pull the hood and go for a long drive. The fuel filter before the carb is glass so I should be able to see if it is indeed starving for fuel. I've changed nothing on the truck's fuel system in many years, so this is a really odd problem.
