the first time you change one of these filters it may drive you crazy. note that the new filter has a rib (for lack of a better term) near each end. this rib is what holds the filter and line together. inside the end of the line is a stainless steel circular clip with 3 or 4 little fingers on it. when you push the new filter on to the line you feel/hear a click. that's the rib snapping behind the clip. i mention this because it's important to know how it works before you try to get the old filter off. the first time i changed one of these filters it took me 2 hours over 2 days. now i can change one in about 1 minute.
you take the tool and insert it into the end of the fuel line and press it in while pushing the filter into the line (i use the 5/16" size tool) doing this gets the tool to push the fingers on the clip in, then while holding the tool firmly in place you should be able to remove the filter from the line. repeat the process on the other side. installing the new filter is easy. just push it in until you feel/hear it click.
tips: if you have dirt or rust in the clip it's hard to get it to release. rotating the tool can help release all the fingers of the clip. i prefer the metal tools to the cheap plastic ones. i got a set at Autozone for $20 and they work better than anything else i've ever used. i usually wedge a pair of pliers between the tool and filter to help push it in. if you ever try to release the line from the fuel tank fitting, use the 3/8" tool. if you damage a metal clip, they are replaceable and available at most auto parts stores.
