I just went through the same BS. There is a good vid on You Tube called 'Configuration of fuel lines on Poulan 2150'. The short of it is the small line on the primer bulb goes to the lower nipple on the carb and the small fuel filter line goes to the upper nipple. The larger line on the primer goes back to the tank. Lines are difficult to get through the holes and you need to cut a long taper on the lines so you can find then. Silicone grease on the lines helps with pulling them through once you locate the taper. I bought an 11" set of needle-nose pliers for that purpose ($3.99+tax at Harbor Freight) because nothing else would reach through the gas filler hole. It all worked fine. Good luck!