I put a new fuel filter on my car (2002 Citroen Saxo, 1.1 petrol engine) yesterday - pretty simple, just unclipping the lines from the old one and putting the new one in the same place. It's located at the rear, right beside the tank under the car. I should have blocked off the lines before unplugging the filter, but I didn't have anything to hand so I just did the swap as quick as I could and lost some fuel in the process.
After doing it, the car took about 5 seconds of cranking to start up - and ran fine for the rest of the day. I started it twice more after sitting a few hours each time, and it fired right up. When I started it again this morning though, it took another 5 seconds or so to get running - almost like there wasn't fuel at the injectors right away. This makes me think - do I need to bleed the system somehow given that I let fuel leak out? I would have thought any air would escape through the injectors but I might be wrong! There's no leaking from the new filter by the way.
Attached is a photo of the old one, showing you how it's set up. This is the 'out' end, which has two lines (I'm guessing one is a return line from the fuel rail).