Su-27 engine stop while flying upside-down ?

[Majesco]

Since LOFC 1.1 to now i just know that Su-25A/T engine can stop while flying upside down and it has been concerned in the flight manual. 

But, last night i flew both Su-25A/ and T upside down about 2-3 minutes and saw nothing happened, those planes engine didn't stop ??? 

But the Su-27 engine will stop after few seconds flying upside-down at any airspeed or its engine could stop about 2 seconds while getting altitude.  

Is a bug or Su-27 flight model has changed ? 

[Raven (Elysian Angel)]

It's not about the flight model, but how fuelling is modelled. Engines flame out in such conditions when the fuel pump is unable to get the fuel out of the tanks and into the engines.
FC3 has highly simplified systems modelling, but perhaps there is a line of code added to emulate that anyway...