240SX RMS, fuel cutoff problem - brainstorming needed

[Gogach]

So, 1991, KA24DE. Problem is this. When gas tank has less than 20L of gas, on very sharp turns, car gets a fuelcutoff, like there engine gets no fuel. 10 seconds after turn, car continues normaly.

Same thing when car has less than 15l, when the same thing happens on normaln curves and even on uphill movement.

Tryed to change fuel pump, fuel filters, opened gas opener to check if there is to much vacuum, checkd for gas tank if there is any garbage inside... NOTHING...

Any ideas?