Think the pootling is the problem!!
Filter would be my first thought, not let the level get too low and sucked up muck.
Not been using supermarket fuel for to many fill ups, I try and get a good brand BP or Shell in every so often.
I also put in 2 cup fulls of Millers Sports Derv additive, makes it go quicker they reckon.
Know the bleed off pipes can leak, no other air leaks on the derv pipes. Take the cover off and have a quick gander, should show.
Hope you can sort it
