Ok here it is master cylinder 8mo old booster 8mo old changed front calipers and pads no leaks from any lines rear brakes still may need changed but after ive done all the front end brake work I should have some sorta brakes right well pedal builds as long as the truck is off but soon as I fire it up it hits the floor its an 89 f150 4x4 5spd also does have rear abs a hydraulic sending unit for the abs and abs module which I know nothin about abs systems dont wanna sell the truck but if I cant fix the brakes ill have to so anyone that can help would be great thanx for helpin

 

Did you bleed the system when you changed the master cylinder and calipers? Also check the poportioning valve sometimes they will let air into the system but not leak fluid.

 

You seem to have run out of periods. Here, take some of mine. ..............

 

Too funny.

 

Yep. Bench. Bled. The. Master. Cylinder. First. Then. Put. It. All. Together. And. Bled. The. Entire. System. Havent. Checked. The. Poportioning. Valve. Will. Have. To. Check. It. Out. Got. A. Few. Other. Things. To. Check. Also. That. Enough. Periods. For. Ya. Sean........................................

 

Not enough commas now

 

Double check for a leak. I had a leak right under me and didn't notice it, even after I was under my truck feeling all of the lines. I thought it was my master cylinder.

Are you losing brake fluid? Have you made sure your bleeder valves are on properly? All connections on the master cylinder are on properly?(not on an angle)

 

Ahh missed this guy.

 

Just a thought, since I don't seem to consistently get brake pressure all the time either, but could this be a problem with a loss of vacuum somewhere?