Ok I have a stihl 041 farm boss that I have been working on. It has a new fuel lines from the tank to carb and inside the tank. It also has a new impulse line. The fuel line is clear, so I can watch the gas being pumped. I can get it to run off of some gas in the carb and it starts to pump gas but when pumping gas, I noticed there is air in the fuel line. How is this possible after I just put new lines on it? Is the carb the problem? Should I try the carb from my 041av? I was not able to find an answer using the search button. Thanks for any help because currently I am stumped.