i am havin horrible luck with my 91. among other issues i found out the other day that i have a broken motor mount. while i was in my drive way, with the truck in drive foot on the brake i hit the gas like i am gonna burn out. then the large vaccum line the connects the tbi to the brakes(not sure which is which, booster/master cylinder). i cant move it with my hand when the truck is running but it pops off pretty easy, while holding the brakes and pressing the gas. any thoughts

 

That goes from the intake (vacuum source) to the brake booster (the black puck like canister) to assist in brake force applied to the master cylinder (the aluminum part with the fluid on top). When you push the brakes, it should conatain vacumm making it even harder to just pop off. I would guess that the fitting on either end could be loose and worn because its not holding on very tight anymore. I suppose if that tube is clogged at the intake end, then there would be no vacuum and when you pushed the pedal it would blow the fitting out, but you would have no brake assist and the pedal would be hard... Get us a little more into and maybe a photo of whats happening and where? Can you hear any vacuum leaks when you push the pedal?

 

it doesnt do it under normal driving conditions. (so far) it has only happened when i hold the brake and hit the gas like i am gonna do a burn out. it did do it the other day when i romped on the gas real hard at a dead stop, then it made the engine rev around 1600 rpms at idle and i could barely bring the truck back to a stop.

 

Which end is coming off, is it something that a tight zip tie can fix? Or some epoxy?

 

yeah i was thinking of a zip tie also. its the side that attaches to the brake booster. i was just wondering why it happens. thanks for the help ohsofly

 

Just my opinion... why don't you get the line replaced? Sounds from your description that it could possibly be the original vacuum line and if so, 20 years old, it's most likely hard and non pliable and therefore won't stay on the brake booster fitting. Did you replace your broken motor mount?

 

not yet on the motor mount! shouldnt be to difficult though because i dont have any fender wells. i am plannin on replacing alot of the hoses, among other things, when the weather gets better around here. for now i can drive to fast anyway so it shouldnt be too big a deal. thanks guys

 

quick update:
i was driving to work this morning and notice that my rear brakes are catching/partialy engaged. they are making a sound that can only be described as a humming sound. when i press the brakes the noise goes away when i release them its back. could this be popping that line off???

 

All that line does is to supply vacuum to your brake booster, the brake booster assists you to apply brake pressure to the master cylinder. after that it's just hydraulic lines to your calipers and drums. But I would check your rear brakes for starters for that noise. could it be you have a bit of debris trapped inside your drums?

 

i guess that anything is possible with this thing nowadays. lol! i plan on doing a complete brake job next weekend. thanks guys. i hope this clears up the majority of my issues!