I call them Weed Whackers. Two stroke gasoline engine that you have to add oil to the gas. So it ran fine the first time I used it this year but the second time I started it up it wouldn't rev. Wouldn't go fast enough to over ride the clutch and then it would die. Figured it was the old gas from last year so go new gas. Added oil to gas. Dumped old gas in Echo. Then tried again. Still no go. So wasn't old gas. Set it aside, tried again a few days later. Searched for this problem on the net and found a You Tube that showed where the idle speed and mixture screws were but mine apparently, a newer model, has no idle speed or mixture screws. The carb is not adjustable. So played with starting it over and over then, all of a sudden, it started revving up fine. It started running well again. So a carb that has no adjustment screws. Does it have diaphragms and one of these got a small bit of dirt in it? When the dirt got washed away it ran good again? Is this going to happen often? Is there anyway I can fix it faster the next time?