If under 3/8 of a tank there is exactly 5L of fuel on the right side and everything else is on the left side.

There is a well on the right side where the pump is that holds 5L then it floods over to the left until the left is full and the left and right are combined and fill together. Below about 27L the system is entirely dependent on the transfer pump filling the 5L pump well.

Pull up test six to see what it says is on the right side. If it's not ≈ 1.4L then highly suspect as the problem.

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