I have a 6500 KW K.C. generator (model # KCG-6500GE) The gen sat idle for about 6 months (fuel tank empty) but when I re-fueled and attempted to start it, the choke check valve and tubing tore apart. I have since ordered a new complete check valve from a local supplier but before I attempt to re-start the machine after I fit the new valve, what caused the problem to begin with and what must I do to prevent a re-occurance?