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Vacuum schematics 1991 Suburban Help please

Discussion in 'General Chevy & GM Tech Questions' started by 91SUBURBEAST, Jul 11, 2011.

  1. 91SUBURBEAST

    91SUBURBEAST New Member

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    Does anyone have the vacuum hose schematics for a 5.7 throttle body 1991 motor. The previous owner made a mess of my vacuum hoses and I need to fix them. Any help would be greatly appreciated. Thanks in advance.
    #1
  2. Crawdaddy

    Crawdaddy Moderator

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    There should be a sticker on the front radiator core support the describes the emissions setup with vacuum hoses. I'll try to get a pic of mine later tonight. For the other vacuum hoses, a Haynes or Chilton manual might have it.
    #2
  3. 91SUBURBEAST

    91SUBURBEAST New Member

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    Thanks I appreciate it. Haynes definitely doesn't have it but a chilton might. Any help would be appreciated.
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  4. MightyMax

    MightyMax New Member

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    If it would help, I could snap some pictures of my truck and post them.

    It is a '91 350
    It has had an Eddlebrock Intake put on it, but still stock TBI

    Let me know and I will post it.
    #4
  5. 91SUBURBEAST

    91SUBURBEAST New Member

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    That would be allot better than where I'm at right now...can you please post pics of your truck.
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  6. MightyMax

    MightyMax New Member

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    This is looking at the TBI from the front.
    There are 3 hoses, the one on the left goes over to a sensor, I can't recall its name
    The one in the middle goes to the valve cover, the one on the right w/ the black plastic wrap around it, is coming from the canister behind the headlights.
    That line inbetween the left and middle hoses, is a bundle of wires for powering the injectors.

    IMG00107-20110713-0656.jpg


    IMG00108-20110713-0657.jpg


    This picture is from the back, there are two fuel lines and the hose in between them goes over to the MAP sensor.
    IMG00109-20110713-0657.jpg


    IMG00110-20110713-0658.jpg

    This is from the back of the TBI also, just from the driver's side of it.
    IMG00111-20110713-0658.jpg


    That is the MAP sensor I believe that the hose on the back goes into.
    IMG00112-20110713-0658.jpg


    Hope this helps you.
    Let me know if something else is needed.
    #6
  7. 91SUBURBEAST

    91SUBURBEAST New Member

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    Thank you! This is definitely not how mine are currently routed. Now I can fix them and diagnose any other problems from there. Thanks again!
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  8. MightyMax

    MightyMax New Member

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    Welcome, let me know if you need something else.

    I will use a better camera then....that was with my phone, which isn't the best. :(
    #8
  9. 91SUBURBEAST

    91SUBURBEAST New Member

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    Lol...I know when I blew them up they were all digitized. Thanks still the descriptions are really helping.

    ---------- Post added at 09:22 AM ---------- Previous post was at 09:09 AM ----------

    Ok question...on the map sensor there are two hoses. Which one goes to the throttle body and which one goes to the vacuum canister on the intake? Also there is another vacuum line at the rear of the intake manifold where does that connect to? There is also one more on the firewall itself going to the round canister by the firewall where does that attach? Thanks for all your help.

    ---------- Post added at 09:27 AM ---------- Previous post was at 09:22 AM ----------

    I'm sorry it isn't the map sensor that those other hoses go to its the rear if the sensor the neither of us know the name of lol.
    #9
  10. MightyMax

    MightyMax New Member

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    Ok, I think that sensor is the EGR Control Solenoid


    The one you mentioned on the firewall, is that located on the driver side of the firewall??
    Big round thing??

    If so that is the brake booster, and his vaccuum is attached to the front of the intake
    His hose is located beneath the TBI, and actually goes into the intake on the front side, next to the driver side valve cover.
    If you look at picture two above, that is the line that is located right above the word "PERFORMER" stamped into the intake.

    ---------- Post added at 01:13 PM ---------- Previous post was at 12:59 PM ----------

    That EGR Solenoid is attached to the under side of the Electronic Spark Control Module.
    #10
  11. 91SUBURBEAST

    91SUBURBEAST New Member

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    Ok so which hoses go into the egr? And which hose hours to the smog valve on the passenger side?
    #11
  12. MightyMax

    MightyMax New Member

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    I will give that a look in the morning and let you know.
    Been busy all day, so just saw this now.....


    Waiting for my A/C components to come in, so hoping to be rebuilding my A/C system some time this week. :D
    Oh joy.
    #12
  13. MightyMax

    MightyMax New Member

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    Ok, so a hose comes from the TBI and into the EGR Control Solenoid, the hose on the back of that solenoid goes into the EGR
    #13
  14. 91SUBURBEAST

    91SUBURBEAST New Member

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    Thanks Mighty i have it all figured out now thanks to you but now I think that my TPS is bad...Damn truck.
    #14
  15. MightyMax

    MightyMax New Member

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    Glad to help.

    You can get a volt-meter and test your TPS.
    You will just need to get some sort of probe that you can stick down where the wires connect on him...
    I used a straight pin for mine, with gator clips.

    (You may need a second pair of hands also)

    once your probe is set, then just move the throttle through its range of motion and the voltage should increase/decrease accordingly.....
    TPS is easy to replace, but I doubt it is your problem....
    What exactly is the issue you are exprienceing?
    #15

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