I have a John Deere GS30 walk-behind that I rebuilt. I put a brand new engine- Kohler 15 on it in April. It runs great once I get it running. The problem is after it sits for a while (couple days or so) it will start fine but then start sputtering and die. It runs a little better on choke but eventually will die. At first I was able to get it running again. After happening a couple times, I took the fuel line off BEFORE I started it. I just let the fuel drain on my driveway and it looked like tea for about 2-3 seconds and then was like normal gas. Hooked up the line and it ran FINE for hours. Everytime I want to use this machine- I have to repeat this process: take line off- let it drain until it is clear gas, hook up and start. IF I don't the engine runs for a couple seconds until (I'm guessing) the fuel in the carb is used up and then it dies. WHY? The fuel line was new in April AND I put a new fuel pick-up in it. This is a siphon system- not gavity feed. Any ideas? New fuel line?