I have some brake pressure on my 77 land cruiser but not brakes. I can bleed the brakes but nothing happens when I apply the peddle pressure.

Definitely try bleeding all the air out of the lines first, but if that doesn't work, you may need a new master cylinder, brake booster, or both. If you pump the pedal do you eventually start to get a little bit of response from the brakes, or is it still nothing at all, even when you pump the pedal?

I have replaced the brake booster, master cylinder, and most of the brake lines. I have bled the master cylinder and all four wheels numberous time. I get good brake pedal when the engine is off but when I start the engine the brakes get extrememly soft. The brakes work but not until the pedal gets all the way to the floor. The back brake cylinders have been replace and the front calipers and pads. The back pads are over half way and still good.