1997 Civic HX 5MT stock 315k

Do I need to open both the fuel filter line and the fuel filler cap to relieve fuel pressure to work on some things ?


I was doing an EGR passageway cleaning (the 2nd one of this car's existence) and to relieve fuel pressure I started the car and removed the fuel pump fuse while it was running, then I cracked the fuel filter banjo bolt a little bit until the usual bit of fuel came out. I didn't finish the job right away for various reasons and had to let it sit overnight to come back to the next day. The next day when I got back to it there was fuel on the ground all over the place. It was coming from the filter banjo bolt area; I had the fuel pressure regulator removed to do the passageway cleaning and left it removed overnight but nothing had come out of that. I removed the banjo bolt completely when I noticed the leak and fuel gushed out of the filter top. I quickly put the banjo bolt with its old washers back in until the fuel stopped coming out.

Why was there still fuel pressure coming from the feed line through the filter ? How do I completely depressurize the system ? Should I have also opened the fuel filler cap to depressurize ?