I have a fuel barb and length of fuel line all rigged up for this purpose. Had to do it on one of my older boats. Undid the line at the fuel/water separating filter head, hooked it onto the barbed fitting on the line I made up, hooked the other end of the line to a electric drill pump, and had the tank emptied in no time. What are you going to do with the old gas? I wouldn't trust it even if you treated it with Sta-Bil given how long it has sat.