I have a 1995 4runner with the 3vze v6, 219,000 miles, auto trans, 2wd. it was running fine except for a leaking valve cover gasket. I pulled off the intake plenum to reach the covers and noticed a lot of carbon buildup. so I removed the intake manifold to clean it out also. I replaced all the gaskets associated with this. after putting it all back together I started it up and everything was fine (it might be running a little rougher). as soon as I push in the brake the engine stalls out after a couple of seconds, I removed the vacuum hose from the brake booster and plugged it, now it doesn't stall. I am thinking that it is a vacuum leak but all the lines appear to be fine. any help would be great. Thanks

 

sounds like you missed a vacuum line when you removed the intake plenum, follow that brake booster line you should find it sounds like.

 

I have checked all of the vacuum lines, all are hooked up and in good condition, where else could I have a leak besides the lines

 

Sounds like you've already confirmed it's the booster.

 

I was thinking it could be the booster, however before i took the motor apart to replace all the gaskets and clean it, it ran fine. now thats its back together I haven't even taken it for a test drive because I couldn't even push the brake in to get it into gear without it stalling. I just find it hard to believe that the brake booster went bad while just sitting in the garage, and I also find it hard to believe its the booster after all the stuff I replaced. I would hate to buy a new booster and still have the problem. I torqued everything to spec and in the correct order, but could one of the gaskets still be leaking? or could the NEW pvc valve be bad? also is the a way to check the check valve that is in the hose between the intake plenum and the brake booster?

 

ok I got a chance to attempt to take it for a test drive today, I disconnected the brake booster and plugged the line. pushed in the brake and all was good (of course it was, there was no vacuum going to it) I put it into reverse to back out of the garage, rpm dropped (again of course, the engine now has a load on it) I waited a couple of seconds to see if it would stall out while in gear, it didn't, then slowly released the brake to back out and it started to stall again. not the booster, must be a vacuum leak, but from where? all of the line look fine with a visual inspection, could a small vacuum leak cause all of these problems?

 

Hmm, you sure about the connection between the brakes and the stalling out? Can you check again, with the booster vacuum line still plugged?

If you're very sure about that, also try turning on your headlights. There could be a bad connection somewhere that's robbing power from the engine electrical systems when the lights are on.

 

ok had some more time today to look for a vacuum leak. found the the underside of one of the intake hoses (after the MAF and before the TB) was cracked and causing a small vacuum leak. going to fix that today and see if that helps at all.