i having a brake pedal issue were i bleed the brakes engine off the pedal is hard start the engine you can easy push the pedal to the floor i have rebuild all brake calipers fitted new maste cylinder fitted front braded brake hoses i have bleed the system now 14 times and still no change what the hell in going on

bled the abs unit?

yes i have bled it in all kinds of ways its all great till you turn the engine on could the brake booster be leaking what the symtoms of s fault brake booster

with the engine on if you get your head rite in the foot well and press the brake pedal with your hand you can hear a hiss as the pedal goes down could that be the air from the rubber boot on it of the air leaking out

Check round the brake booster area for rust holes;

 

http://www.300zx.co.uk/forums/showthread.php?170588-Brakes-not-working&highlight=brake+booster

 

http://www.300zx.co.uk/forums/showthread.php?134740-Braking-problem&highlight=brake+booster

i all look i very good nick nothing link in that link but the air must be geting out when i press the pedal i have bleed the brake so mant times and it never changed a thing the master cylinder is brand new the calipers are rebuild its only the master cylinder left look like am going to have to replace that now to am starting to hate this a lot