Yes, top of the fuel filter housing is favourite. I had a leak on mine last year, (it leaked fuel and ultimately cost me an alternator). I tried re-sealing it and eventually replaced the whole housing before curing it. Hope yours is easier.
2002 HDi 2.2 Exec Estate, (2008-12) (wonderful)
2003 HDi 2.2 6-speed Exec Estate (2012-19) (also a gem)
2009 Citroen C5 2.0 HDi VTR+ Estate (godawful heap)
2008 BMW E91 330i touring (great fun - murdered by a reversing SUV)
2007 BMW E91 325i touring (slower smoother quieter)
Good point rwb i assumed it was replaced approx 6000 ago but before that i had a chirpy aux belt and a friend and i had the amazing idea of putting some talc on it.
It worked but my bonkers mate put some more on for good measure and it went everywhere. including the fuel filter housing which doesnt look like its been touched. So. I wonder if its wasnt changed by the old boy down the road who has always done my small service.
I got a aux belt 3mm longer which sorted that but hmmm. Fuel filter is a stronger suspect methinks.
I wont have a go at the old boy even if he didnt as i think he's over 300 years old.
I cant decide if there is more air in the clear fuel line than before which makes me think theres not. So would a blocked up fuel filter cause the faults with Flow regulator at stop. I dunno. Cant do today but will update. Its run great today no probs at all.
Thanks for your attention to my problems with my motor. Who would've thought it was only a fuel filter. Expect the unexpected and look for fingerprints on the fuel filter. There were none. That was a clue....