Fuel tank pump issue, level sender issue

[andrewwynn]

Find my detailed master thread on the fuel supply for the e53. Search for my username as started by. awr-fix should also be in the title. There is literally no more detailed description on the internet. Not even from BMW. They copied boilerplate from 5 series that doesn't apply to X5.

Some of the top points:

1) the electric pump is on the right side
2) the pump pushes fuel at roughly 65 psi to the fuel pressure regulator and filter
3) the FPR sends 50 psi to the fuel rail
4) the excess fuel pressure is used to send fuel at ≈ 18 psi back to the left side of the tank
5) the flow back to the left side goes though two venturi valves to suck fuel from the front and back to the pump well on the right side
6) there is a design defect that will eventually cause that Siphon jet to fail. Usually by 15-17 years or 130,000 miles. That can be fixed for a couple $ vs. replace the whole pump
7) when that fails you will fuel starve the engine when about 1/4-3/8 tank
8) once you are lower than about 28L of gas the car only "sees" about 5.0L of fuel, about 3.6 of that is not registered on the gauges.
9) the fuel filter is for all practical purposes lifetime, it can easily last 400,000 miles. However the FPR has an o-ring that will fail causing low and unstable pressure. They are usually sold as a unit.