all you brake guys please read

ok i have a 90 s-10 that i just had tubbed on 20s so i had to change the stock booster because it was to big so i changed to a 7 inch booster a buddy found on ebay i think but anyways i changed it and didnt have to modify anything for it so i bled the brakes and the pedal pumped fine until all the air was out off the line when i went to drive it and applied the brakes the pedal moved about two inches and stoped and my front brakes locked up so i was told change the front lines and i did the brakes didnt loke up but still the same prob with the pedal the only thing i can think is that the booster is bad which i can get another real easy any of you guys have any ideas? thanks in advance

Did you change just the booster or did you do anything to the master cylinder too?   How did you bleed the brakes?    

i just changed the booster what do you mean how did i bleed them like with the truck running or off? if thats the case i did it with the truck off other than that just pumped the brakes while a buddy bled them starting with the back passenger then back driver then front passenger then front driver i was thinking the truck needs to be runing while i bleed them so it with pull a boost but everyone i talk to says it dosent matter

Yup, it does not matter if it is running or not.  I was making sure you bleed it starting from the furthest brake away from the master cylinder and working your way to the closest.     It sounds like you still have air in the lines.  I could be wrong, but there is not much to brakes.  I had the same problem with my Yukon and it ended up having air in the lines and my brand new booster was bad too.  This might not be the same scenario for you but thats my experience thus far.     I would try to bleed them again to make sure and be sure to get the air out.  I use those one man bleeding kits now, and dont have the problem with someone accidently opening or closing or letting go of the brake pedal, ect ect.     I would try to keep it simple at first.     Good Luck! 

ive bled them three times or so and they have a heavy stream of fluid coming out if it had air in the line wouldnt it just go to the floor? i think im gonna try another booster my buddy bought four of them for other projects and he said come get another one but thanks for all your help

are you sure the push rod was the exact same leingth on the new booster?

i never looked but i thought about that then came to the conclusion that if they were different then when i bled the brakes the pedal wouldnt have went to the floor like it did, it bled normal but when we finished bleeding then the pedal was stiff and moved maybe two inches and stops

ok so i thought about something maybe you guys will know does anyone know if a stock 90 s-10 booster is single or dual diaphragm?

bump i really need to know

it is possible to have a bad booster. My brother changed his booster on his 70 chevelle and bought a brand new booster and was bad. he returned it after similar trouble and 3 or 4 other new boosters got a good one. the booster i am runnin on my s10 i swipped off my buddies early 80s model s10. he had a parts truck with a big booster so we traded out those then i changed the rod to fit my truck. its like a 9 inch booster i think. but it lets me drag body and turn a lil on 20s.