The Craftsman Sim-Pul string trimmer starts and runs for one sec.

The larger line is the fuel return line from the purge bulb and should have the nylon connector (funnel thing) on it holding it in place inside the tank so the line won't pull out.The smaller diameter fuel tank line goes from the tank to the lower pipe fitting on the carburetor (fuel intake line). This line has a weighted fuel filter inside the tank on it.
New fuel lines are recommended every so often as the ethanol added to our gas nowadays wreaks havoc on the lines and carburetor as well. Get new lines...cut them long....feed them thru holes in fuel tank...grab with tweezers or needle-nose pliars....put on either the fuel filter or the nylon retaining nipple and pull the one with nipple down to bottom of tank...one with fuel filter can stay long to help draw fuel in the tank (yes, it moves around and is supposed to).