I was flying a C152 from NYC to Miami, Florida and it didn’t run out of fuel after a few hours. I had to abort the flight because it was taking too long to fly that airplane. I tried again with A320 and it ran out of fuel and its engines shut down. I had to land the airplane on water much like real-life pilot landed a jetliner on the Hudson River after bird strike damaged the engines.
Known bug, unlimited fuel only works on some aircraft.