s p
Have you open your bleeders? The most likely problem is your rubber brake lines have collapsed. Try replacing these first.

wayne h
bad master cylinder , empty due to leak in line, mashed line not allowing it to get there ,hard to say not knowing more

Rudedude
could be a couple of problems. Your master cyl could have gone bad or the proportioning valve maybe no good. Trace which lines go to the rear brakes from the master. Crack one of those lines and have someone slowly push the brake pedal to the floor. Look for fluid coming out of the line.Tight the line before they let the pedal back up . Fluid flow means master ok . Do the same at the prop. Valve if no fluid there your problem if not take it some where as this is over most peoples heads and you could throw lots of parts at it and miss the problem. Good luck hope I helped

yes_its_me
Check the obvious and then proceed. 1. Master cylinder has two compartments. Pop the cover and see if there is fluid in both. Pump the brakes, you should see turbulence in both compartments. You may have a bad master cylinder. 2. Proportioning valve. In line between the master cylinder and the rear brakes. Crack a line and pump the brakes. See if fluid is getting past it. If not, replace the valve. 3. Inspect the brake lines for damage/leaks. If none observed get a good pressure bleeder and pressurize the whole system and do the bleeding again.

Onlychrist.net
there is this proportioning valve in between the brake system that may have went bad check that out.

citgo25
i think you have try to bleed the brakes you could have a air pock in the line or a loose line end or a bad porinsh val. to tell you whate is goneon i need more infor.

mike m
bleeder vlaves plugged? or brake hoses collapsed.

drvshaftdrew
try bleeding