Two things to keeep in mind. You need special fuel grade PVC Tubing. Tygon brand is yellow and fairly expensive at $.75 to $1.00 a foot. The clear stuff at Home Depot and Lowes is OK with fuel and much cheaper ($.15 - $.20/ft) but the sizing usually won't work. Correct tubing from McMaster-Carr in Tygon is 5555K43 9/64 OD x 5/64 ID and 5555K22 3/16 OD x 3/32 ID. Both are about $.75 per foot. You need to measure which one is appropriate for your machine. Size is critical, because too big and you won't get it into the tank; too small and the tank will leak where the tubing passes thru.

Second item is to install in tank. Homelite like other cheaper trimmers does not use a fitting in the tank. Rather fuel line passes through smaller hole in tank and pressure on tubing maintains the seal. To install you need to cut tubing at a 45 degree or more angle to provide a sharp point. Thread this thru the hole by twisting and pushing gently. When you get enough through, you can then grab the end with needle-nose pliers and pull more through. Cut the end off square and push on the filter/pickup stone. Then pull the excess tubing back out of the tank, leaving enough of a service loop to permit the stone always travel by gravity to the lowest part of the tank. Usually three inches is about right. Now connect the other end to the carburetor or purge, and you should be good to go.