The diagram above is NOT from e53. Read my thread it details all aspects of e53 tank and why it is different from all other fuel tanks.

ALL of the fuel goes into effectively a 5L gas tank. The car is unaware that the tank holds more than 5L of fuel because once there is more it spills out over to the left side. This starts at approximately 27left 1.5L right. Once below about 28L total the right size will report 1.4L or so (the last 3.6L is unreported).

The fuel does go in circles which will cool the liquid more than if it was just the 5L but there is never more than 5L surrounding the pump once the total fuel is about 28L of gas. (30%).

Yes, really. The bottom of the right side of the tank is approximately MIDDLE of the depth of the left side. The surge tank is in the back of the right side and it's a "dent" who's top lines up with the bottom of the right lobe of the tank.

See my diagrams and photos. Like I said, after 25-30 hours of research I found ZERO accurate pages describing the workings of the E53 Fuel pump. They all used inaccurate references based on the sedan designs and were wrong, every single one.

When I eventually figured out exactly how it works (even siphoning out the surge tank to determine it's exact volume) I literally know more about the E53 pump than any accessible resource online so I shared that info with xoutpost because they are deemed by me to be the most worthy of my contribution.

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