k so i have 95 accord with 96 prelude motor, and i was driving down the road the other day and my brakes randomly went out. The brake pedal has no pressure to it what so ever when the car is on, but when i turn it off, it has full pressure. Any suggestions?

 

check fluid level: If it's not full, look for leaks.
If it is full, test master & slave cylinders.

 

Yep, check for leaks at the master and slave cylinders and calipers if you have to, then bleed the whole system GOOD to make sure there's no air bubbles.

When you turn the engine on it provides vacuum to the brake booster which changes things in brake pedal feel. If you have air in the lines the pedal will feel good when the car is off, but once you start the engine that vacuum power will 'reveal' the air and make the pedal very soft.