So i have a 1990 240sx no abs and it had been leaking brake fluid from where i can only assume was the master because it would leave a big ol stain on the driver way right under it. Well this last week it had been sitting and when i went to go drive it i checked for fluid it was near empty so i filled it, went to start it and there was no brakes, pedal went straight to the floor. I left it alone and thought maybe it just needed a bleed. I came back the next day and bled it RR, LR, RF, LF and still no brakes. Pedal felt almost "springy" there was no resistance when it was off and when it was on it was soft, i would pump it while it was on and it would get a little stiff but go soft right after. The weird thing is that only the front calipers have air the rears had no air what so ever. I was like well maybe my brake master finally gave a poop on my so i replaced it, bench bled before throwing it on and then started bleeding the brakes again this time LR, RR, RF, LF and still the same springy pedal and again only air in the front calipers but this time it was much less air. So right now im not sure what it could be.