Almost certainly siphon jet. Search for awr-fix in title and look for the fuel supply thread that includes how to fix the Siphon jet.

Did you never drop below 1/4 tank? Once the Siphon jet fails you won't be able to use fuel below 1/4 tank. As it gets worse 3/8 tank.

There's a design defect that will eventually allow the o-ring to push out of the groove.

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2011 E70 • N55 (me)
2012 E70 • N63 (wife)