Young Thug faces more felony charges on weapons and drug possesion.

Young Thug's list of legal problems piled up while he sat in a jail cell ... because he's now facing 2 more felonies on top of a weed possession charge.

As we reported ... the rapper was arrested Saturday in Georgia by Brookhaven PD after he was pulled over for tinted windows. According to the police report, the cop searched Thug's Maybach because it smelled like marijuana ... and found drugs, 2 guns and almost $50k in cash.

YT and 2 men with him in his car were arrested and taken to jail. Thug's now facing a felony charge for gun possession, a felony charge for drug possession -- for narcotics and liquid codeine found in his car -- and the felony charge for weed.

He's still got the tinted windows charge, too.

Thug appeared in court Wednesday, posted bond and is now out of jail.