i have a d100 - 31p677-0236-G1. 2010 model . I am assuming a line or pickup tube is stopped up. before i start blowing air and possibly mess something up, I was wondering what the smaller gas line coming out of the tank is for. I have read fuel return line on some models , or vent line on others. I am used to my older 2005 la115, which is simple one gas line with a vent hole in the center of the cap. fuel shutoff is ok on bottom of carb. changed out fuel pump.