Ok, first of all- thank you to the many minds that have saved my life in the past. I figured it was time to start participating and not just consuming. HOWEVER, my question is: is it possible for a loss of vacuum pressure (through cracked or torn line) cause all the following issues: climate change controls stuck on vent, 4WD not engaging, and fuel pressure issues (vehicle wont start if left off for too long)?

Thanks for your thoughts!

 

yeah possible especially if all that stuff is on one line, all that stuff is controlled by vacuum

 

got the exact same damn trouble right now - pretty sure i've got fluid sucked up from my t-case from when my switch failed. note on the starting: truck starts best for me if I turn the key to 'on', pause and wait for the fuel pump to finish its little run (~5 sec), then twist the tail.

puzzler for me right now is that the t-case is NOT over full - but the OEM blue stuff was dripping out of the vac lines when i changed out the switch. all i can think is enough splashes around in there that if the seals in the switch are gone it still gets sucked through.

post back if you get it figured - it'll be a while till I get to mine - I've closed the face vents and it seems to force enough air up to the defrost to get me by for now

 

Year, make, model & engine would be very helpful here.

If it is a "W" or "X" engine, the fuel pressure regulator does not have a vacuum line attached to it, so fuel pressure would not be affected. The HVAC and 4WD would be affected by a faulty vacuum line.

 

please help new to this site how do you post

 

It is a 2000 S10 BLazer 4.3L 4WD not sure engine type

 

Glad I came across this thread. I am having the same issues, except for the starting issue, as the OP. I also have 2000 4.3 4x4. We recently did a motor swap on it and I have been wondering if I have a vacuum line issue. I am new to these vehicles, it's my wife's who had it before we got married, and I am trying to learn as much as I can so that I can get it all fixed.

 

FIXED IT!!!
happened to be poking around my vac lines under the hood and found this loose and flopping about:


After some head scratching and looking about with a mirror I found it went here:


on this nipple hidden away underneath and in the fender:


I thought the 2nd gens diddn't have a vacuum reservoir - turns out GM just hid it in the fender!

Once that was re-connected I then determined the vacuum line was also split right down at the transfercase...again...
Did this as a temp fix till I can get a roll of vac line and re-run it:


oh - dunno if this will fix the starting issue - truck hasn't been off long enough yet - thinking that may be a separate issue and might need to do the ol' leak-down test on the fuel system

 

Thanks for posting the pics!! I am going to go look under the hood now.

 

you can fold the line headed back to the t-case over double like a garden hose to see if the leak is back there - I set the vent to defrost and when i pinched the line it would finally switch on properly

The little skinny black tube on the right heads into the cab for the HVAC controls, the one I've got disconnected goes back here:


(transmission left, front driveshaft right - pic taken facing the rear of the truck)
My hoses under here are cracked/ripped in some places and folded over in other places - I'm going to run new lines