Impreza drain gas in 214 kms, no leak, no engine light

Hi Guys. I have some issue with my car again. My full mileage supposed to be 400kms before, but recently my car started to drain gas and finish the tank about, 300km, then two weeks ago was 280km, last week was 250, and now my starting to running out of gas and feels like "gas got cut off" in 214km. Does any legit guys have an idea what is the problem? There is no leak of gas, no check engine light. The mileage is about 140,000kms.


By the way it's a 1996 2.0 Turbo impreza sti.

Thanks