Dismiss Notice

Welcome To CK5!

Registering is free and easy! Hope to see you on the forums soon.

Score a FREE t-shirt and membership sticker when you sign up for a Premium Membership and choose the recurring plan.

Vacuum line on rear of intake manifold on 87 TBI

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by wolfy87, Feb 5, 2004.

  1. wolfy87

    wolfy87 Registered Member

    Joined:
    Jan 30, 2004
    Posts:
    32
    Likes Received:
    0
    Location:
    near Dallas, TX
    Alright, this is the latest episode on my painstaking troubleshooting of my low rpm/ underload stumbling. Last night I was checking and rechecking all the vacuum lines. I found that the hose coming from the intake directly behind the throttle body was running astray and not plugged into anything. Can't see it being a free outlet vent tube. Since Chilton was kind enough to include a vacuum line diagram for every year truck EXCEPT the 87, /forums/images/graemlins/angryfire.gif I was stump-ed. /forums/images/graemlins/confused.gif The previous carbed years all seemed signifigantly different and its an 80-87 book. Darn greedy Chilton slackers. The lack of detail in those books would even make it hard to work on Fred Flinstone's car.

    Anyone know where that hose should be routed? Looked like there was a vacant inlet on the EGR diaphragm, but the hose didn't seem to mate up to that real well. The end of this hose has a little micro-funnel inserted into it. /forums/images/graemlins/1zhelp.gif
     
  2. dyeager535

    dyeager535 1 ton status Premium Member

    Joined:
    Dec 13, 2000
    Posts:
    26,975
    Likes Received:
    189
    Location:
    Roy WA
    Maybe other TBI truck guys can comment, but I would imagine your truck is supposed to have an EGR solenoid...vacuum line from motor somewhere, to solenoid, then hose from solenoid to EGR valve.

    If the solenoid isn't hooked up, thats probably where that line used to go, although the "funnel" thing has my confuzzled.
     
  3. conoverbandit

    conoverbandit 1/2 ton status

    Joined:
    Jan 23, 2002
    Posts:
    452
    Likes Received:
    0
    Location:
    Conover N.C
    Hello,
    By no means a "pro" at this but I'm having problems with my TBI also, I have a 87 454 truck and the only vac. line comming out of the rear of TBI runs over to the left of the engine( standing in front of truck look towards firewall) and hooks to a small box that has only one vac. line input and a 4 wire plug on top of it. Look there and see if that's where it goes, the other one on front of TBI center goes to the "purge" on canister, right side goes to a small black box at the font of the engine and then from there to the EGR, the one on the left of TBI goes to the A.I.R selinoid for air injector pump I found this on just laying around in engine compartment lol. But like I say this is how mine runs on a 87 454 TBI #220 yours may be different, but maybe this will give you a baseline to work from. Hope it helps.These are from TBI it's self, I can look on intake if you'd like and try to get you a diagram.Just let me know.
     
  4. detailer03

    detailer03 1/2 ton status

    Joined:
    Sep 23, 2003
    Posts:
    108
    Likes Received:
    0
    Location:
    Arizona
    OK, If I am not mistaken, on my 89, it goes to the firewall. There is a Tee there. It is for your vacuum operated stuff in the cab.
    I am at work now, and will check later.
     
  5. Grim-Reaper

    Grim-Reaper 3/4 ton status Author

    Joined:
    Feb 17, 2000
    Posts:
    7,385
    Likes Received:
    0
    Location:
    Atlanta
    sticker missing on the coresuport? it should list where the lines go.

    The one on the actuall intake is the feed line for cruise and the HVAC. The brake booster also ties in from the back. You may also have a water coolant line that often gets left off and by passed because the line is dealer only and $70.

    The EGR on mine feed off the front of the TBI unit. There is 4 connections, EGR, PCV,EVAP, AIR
     
  6. fortcollinsram

    fortcollinsram 1/2 ton status

    Joined:
    Nov 8, 2001
    Posts:
    2,261
    Likes Received:
    0
    Location:
    Fort Collins, CO
    On my 1987 350 TBI, there was one vacuum line in the back of the throttle body and three in front. the one in back went to the MAP sensor, and in the front, one went to the the A.I.R. diverter valve, one to the purge canister and one to the EGR valve, if I remeber correctly. I have had the big block in for about 9 months so it cant rember exactly with the SBC...

    Chris
     
  7. k20

    k20 3/4 ton status

    Joined:
    Sep 9, 2001
    Posts:
    5,068
    Likes Received:
    0
    Location:
    Mineral Springs, NC
    just checked tags on mine, both sb and bb rear vac line goes to map sensor.
     

Share This Page