Thanks Jim. I think your Poulan probably has a reciprocating cylinder pump actuated by crankcase pressure, like the Echo. Max posted a link at the beginning of this thread, to the Echo illustrated parts list, so you can see how it works. You might find crankcase grunge has jammed up the piston so it doesn't move, or more likely, stuck the little pump intake valve. Because no pressure seems to be developing in your tank, that seems the likely location of the problem.
