Also, what type of jet is it? I have seen engines run differently between models. Is there ducting on the inlets? Does it have a 300 series pipe (IDs matter)? Is it a straight pipe or bifurcated? There are a number of factors at play. I presume the previous owner said it ran perfectly? My money would be on the pump though, I would run a large amount of fuel in a closed loop into your fuel can.