Law enforcement sources tell TMZ ... Blueface was driving with a few people at around 3:15 AM but was stopped by cops in the heart of Hollywood at the intersection of Sunset and Vine.

Police say Blueface was pulled over because he was driving with a car that had an expired registration. Cops ran a computer check and found he was also driving on a suspended license.

That wasn't the worst of it. Blueface was ordered out of the vehicle and cops searched inside and found a loaded firearm in the center console.