Every 6 months or so, I fire up my portable generator. This time, it started right up but won't run once I take it off choke. It will run on half choke, but if I back it off a little it starts to starve and will sputter out on me. Runs smoothly with choke on, with or without air filter (it is clean and new). My brother-in-law's machine is doing the same thing this season Any ideas, hints, or solutions? The machine is pretty much brand new. I have had it three years, run it maybe 10 or 12 hours. Fuel has been mixed with Stabil, and I swap it out every two years if I don't use it. Not getting enough fuel?