Fuel line pvc

I should be asking you that question. It depends on what type of connection you are working on. If it has a hose clamp, that would be pretty obvious and you would not be asking. Many fuel line fittings are of a quick-connect style, and have a black plastic ring that is pressed in to expand a spring that does the holding. Expanding it lets it release so the hose can be pulled off. Those are common on older Chrysler fuel filters. Use a needle nose pliers to push the ring in. Ford uses a lot of quick-connects that are definitely not "quick-disconnects". You do need a special tool to get those apart. Those are mainly on their AC lines, and they always leak, so you are less likely to find them on fuel lines.

If you are working on a Ford fuel pump assembly, they use plastic connectors with o-rings inside. There is a plastic locking wedge that must be pried out to release the hose. Then you should find two plastic tabs that have to be spread apart or squeezed together, (I cannot remember), then the hose can be slid off.