On my 86 toyota 4runner i have done an entire brake system overhaul and still the pedal goes to the floor with no brake unless i pump it up then i get an ok to godd brake. Have changed everything List of Brake fixes:
New Rotors
New Calipers
New Front Pads
New Rear Wheel Cylinders
New Rear Brake shoes
Drums Turned
New master Cylinder Twice due to faulty Remans

I have bleed the system 20 times and still is not giving me any pedal unless pumped need some help cause i'm afriad its the booster but i don't want to go that far. I here no leaks and there is not any corrosion on booster. Need help thanks

 

honestly, if you've done all that and still no luck, it sounds like the booster to me

 

But how would the booster just go out. They really ever go they most of the time last forever. About a week before i did all this 3 wheels were leaking brake fluid. The two front calipers had busted boots and one rear wheel cylinder was bad so thats where i was just with leaks. But a long time the brakes would still stop my truck really good with the leaks first push it would stop me an dnot to the floor. It was recently they started leaking alot and they went to the floor from no fluid in the master cylinder but i filled it bad up and it was fine (keep in mind this is before the work)....

 

when you blead them, did you follow the steps specific to these trucks? they have that LSPV back there that has to be blead as well...

 

I have a factory toyota repair manual for my truck and said to bleed the brakes form farthest line from the master cyl and i did this. I know about the Proportioning valve but did not mess with it. It didn't say bleed it in the manual. Its kinda weird because its like the back brakes work better than the front almost. If i stomp down on the pedal the first time it goes to the floor but if it hold it only the back brakes lock up and skid. So i'm not sure.

 

You have to bench bleed a new MC and the LSPV as well.

 

I did bench bleed the master cyl but not the PV i might try have to try it but i don't think it will help...course i've done everything else.

 

/me thinks that getting brakes after "pumping the pedal" indicates where the problem lies: rear wheel brake adjustments.
If you get fluid in before the wheel cylinders 'collapse', brake pressure will build.

 

Step on the brake pedal and repeatedly pull and release the parking brake handle. When you start to feel the handle getting harder to pull, the rear's should be adjusted close to where they should be.

 

Well i'll try that but on the first stomp on the pedal they go to the floor. Then if you stomp them a few more times after you get good brake. Sooo... you think its the rear out of adjsmnt? Hmmm... dunno

 

yeah, I think that if you repeatedly mash the pedal and braking force increases, the rear shoes are out of adjutment.

 

Well tomarrow i ordered a "BRAND NEW" Master cyl to put in again for the 3rd time and i'll see about adj the rear brakes. I'm also going to get another booster and LSPV from a junked yota like mine. Just in case it comes to the master cyl and rear brake adj no good.

 

Abe, gotta highjack this thread for a minute. By brother-in-law and I replaced his rear shoes and a rear cylinder (leaked significantly) on his "new" 86 Runner this morning and are having the same issues. Adjusted the rear brakes by thumbing the adjustment wheel until they just grabbed the drum. Thought all was good and started bleeding the lines. Half a quart of fluid and no air bubbles later, still get little resistance until 3/4 way down on pedal. If we pump them up, good resistance. I cranked her up and let the booster get some vacuum, shut it down and then pulled the vacuum line off the booster after 60 seconds or so. Held vacuum very well, so I don't think it is the booster. Did not bleed the LSPV because the screw broke off after 1/4 turn with 10mm socket. Suggestions on how to bleed the LSPV?

 

does no one remember my issues a week ago read my thread it all sounds similar. Replace your booster and THEN put the new master on.
seriously read my thread don't go through what I did !!!

 

Ok guys update! I got my brand new master cyl in the truck but it did not change a damn thing. It still goes to the floor on first stomp. Oh yea i also tried adjs the rear brakes and tried the pumping and pulling the e-brake but it did not fix anything. So all it at loss and there wa only one more prob it could be THE BRAKE BOOSTER! So i could not find a brand new one anywhere excpet toyota dealer which wanted 500 dollars. So i got a reman from advance auto and its coming in, in the morning. I'm going to put it on tomarrow and i'm praying to god it fixes it because if not then its a freakin mystery.

 

Did you read my thread on this page (sorry no link damn iPhone) its titled "brake system problem please help"
I am sure it will help you! It was such a nightmare!

 

UPDATE!!! I got the new booster and installed it. THAT WAS THE PROBLEM!!! Fianlly after replacing everything in the brake system its fixed i've been trippin out for sooo long now its finally fixed that god. Any way my trucks all good now thanks everyone for all the posts and replys.

 

please be sure what you replaced was the problem. Brake servo's are 'rarely' the cause of 'pump the brakes and it works better', but they can hide other problems.
Pumping brakes to get them working is almost always a sign something else is wrong, like bleeding or adjustments.

 

Dude man i replaced the booster and now it does not go to the floor it is a very firm pedal with superb brake. I've bleed and adjs the brakes all and everyway. The problem was there was a hole in the booster and when you pushed the pedal or pumped it multiple times the engine would bog down and try to shut off. A big indication of booster vaccum leak. So thats what it was it no longer bogs the motor with the new booster. so yea its fixed i've replaced everything there it to replace except that proprtioning valve.

 

I have bled all around and in proper order including the lspv. I have also tried your suggestion of pumping the brakes and pulling the parking brake with no success. Do you think there could be any other causes before I try to replace the master cylinder? and if nothing, then the booster?