My walkbehind is starting right up wiht a few pushes of the prime and one pull, but soon chokes out and dies. I've found if I continually push the prime button, it will stay running. As soon as I stop, it stops running. Does this mean it's not getting enough gas? Also, if I take the air filter off and place my thumb over half of it, it will stay running. So, it's getting too much air? Not enough gas? Wierd. I just had a tune up and have only mowed twice since. I'm definitely taking it back to get checked at no charge to me, but just curious what you thought.