[slonikas]

I have n52b25 e90 2005 and I cant start the car when it has about 15(litres) or less gasoline. When it is over 15L it starts good. Is it fuel pressure regulator? Is it below rear seat on the driver side? just want to make sure. Thank you for your time

[gbalthrop]

Originally Posted by slonikas

I have n52b25 e90 2005 and I cant start the car when it has about 15(litres) or less gasoline. When it is over 15L it starts good. Is it fuel pressure regulator?...

My SWAG would be a problem getting the fuel from the Left side of the tank to the Right side where the pump is located. If that concept is correct, the problem is NOT that the pressure regulator is not working properly, but RATHER that there is NO fuel on the right side of the tank for the pump to PICK UP.

See this TIS Fuel System Function Description, and note how the tank is "saddle-shaped" so that it is effectively TWO tanks, at least when fuel level falls below 1/2 tank on the gauge (combined readings of TWO Level Sensors):
https://www.newtis.info/tisv2/a/en/e...supply/PQ22XEp

There are TWO Fuel Level Sensors in the tank, one on the left (#1 in the diagram), AND #3 in the right side of the tank where the pump is. The KOMBI module (Instrument Cluster) combines the signals from the two Level Sensors to give a "total tank contents" reading on the instrument cluster gauge. As I understand the pump function, the "suction jet pump" is supposed to be pumping fuel from the left side of the tank to the right, so that the left side is empty when total tank level is below the "saddle" or drive shaft hump.

My SWAG would be that fuel is NOT being pumped from the Left side of the tank to the Right side. I've never opened my tank up to examine all the plumbing inside, so can't say how the "suction jet pump" is supposed to work, or whether you have a disconnected/ loose tube/ connector preventing fuel transfer from left tank to right.

This is NOT just over-engineering, but rather an effort to give the "Ultimate Driving Machine" as low a C/G (Center of Gravity) as possible, a full tank of fuel weighing ~ 115 lb. or 52 Kg.

ANYONE actually dealt with that situation & able to offer some observations from personal examination of the system?

Please let us know what you find,
George