i have bled my brakes a few times until i got to where pumping up the pedal while braking wasn't necessary anymore, i belive i finally got all the air out.
( i had replaced 2 rear brake cylinders ).

here is my problem, the pedal is close to the floor, so i put on a new master cyl, still got the problem, bled the brakes about 5 times on each wheel in the correct order..
any suggestions
it is a 1998 f150 with 181k miles
i don't hear any vacuum leaks at power booster- but true fully im not knowledgeable on that part

 

Did you bench bleed the master cylinder before installing? This is done with 2 small screw in adapters and 2 short hoses (in some new master cylinder boxes) or found in the help isle of automotive store. If not I suggest removing the break lines and bleeding it in place. Do it slowly until there is no air left. Then re-bleed all the lines starting furtherest from the master cylinder, make sure to keep it full and it will take many pumps to get to the air trapped in the system out. Hope that helps.

 

i sort of bench bled it, i had nothing to hold the cly so i mounted it in place and bled it with the hoses, i got a lot of air out,but it seemed to siphon back in
. got a lot of air out of each wheel when i bled them, and i did it in the order you mentioned, thanks

 

If the pedal is firm but at the wrong level, check the rear brake adjustment; this is often overlooked, and contributes greatly to pedal position. Yes, they are self adjusting, but the adjust as close to spec as you would play horseshoes.
Pad wear on the front is another area to look at. When worn, the pedal has to travel further to get the distance overcome.

 

thank you so much that was the problem along with having some air in the master cyl...i had to adjust the backs about 10 turns. the self adjuster is wore out..