Braking issue?

[Projectolred]

I have a 93 gmc sierra and just recently when i go to stop my pedal will go to the floor little by little. Does anyone know what this could be? It has over 256k on it now but im not sure.

[Kabnn]

Check your brake booster. If it feels like your pedal is very stiff and doesn't want to go down to the floor, then this very well could possible be it. To check if, engine off, key off, pump the brake pedal until very firm. Then hold down the brake pedal and start the vehicle. If it doesn't move then replace the booster, if the pedal drops to the floor, then it's fine.

[dreese_us]

Could be the master cylinder if the brake pedal slowly drops to the floor with pressure on the pedal. How are the brakes in general? Check your rear wheel cylinders or all brake lines for leaks. Depending where you're at, the metal brake lines tend to rust out. I just replaced the front lines on my 96.