Read my thread on fuel system, if you are "running out of gas" when the tank reads 1/4 or 1/8 of a tank almost certainly it's the o-ring on the left side of the fuel tank.
The gas sprays out into the left tank rather than going into the siphon jet so the gas stays in the left side of the tank.
Use the hidden menu #6 to track the number of liters in the left and right tank.
If the left side is zero and the right side is 1.4 or so the pump is failing.
If the left side has 10-20L and the right side is less than 1.4L then the siphon jet is the problem and almost certainty the o-ring has failed on the siphon jet and you can fix for free with a few wraps of Teflon tape and some zip ties.
Every siphon jet I've ever worked on over 120,000 miles has had this failure, it's a design defect and you can expect every BMW with this style of siphon jet to have this problem about 130-150,000 miles.
The problem will bite you in the ass if you don't periodically run your gas down to the low fuel light or even single digits distance to empty..