I have a craftsman snowblower 208cc OHV. I follow the simple instructions on the snowblower (key in, set choke, , lever to high speed, pump primer X3, then push the starter button). Each time I prime it, it starts, but only runs for 1 or 2 seconds, then stops. If I repeat the process, it does the same. Do you have any suggestions as to what I should try next?