Treerev,
My 031AV did the same thing and I found the in-tank fuel line was softened to the point it was collapsing and cutting off the fuel at any draw above idle and I couldn't pull fuel at the carb end using a hand vacuum pump. I replaced the fuel line and could then pull fuel through the line at the carb, but it was loading up too rich at cutting speed so I am putting a kit in the carb. I sure hope this fixes it, but I'll let you know if I find anything else.
OK, between the new fuel line and the carb kit my 1973 031AV starts and saws like it once did when it was new.
A couple of things to check are the inlet needle and the diaphragm in the carb. The book says if the inlet needle has a worn ring on the business end it will not seal and the engine will flood on high speed and it will also flood if the diaphragm is distorted (bloated looking in my case) making it press on the inlet needle continuously. I think my problem was the diaphragm, but I used the new inlet needle in the kit also. Stay away from gas with ethanol - I am sure that is what caused my fuel line and carb innards to go bad. In Missouri gas must be 10% ethanol by law - thank you big brother! I now buy 100% gas in Arkansas for my saws and small engines.
