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  1. #1

    Default Vacuum schematics 1991 Suburban Help please

    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.

  2. #2

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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.
    Christopher

    1991 Chevy Suburban 1/2 ton 2WD w/ chevy SBC 350-3/4 ton drivetrain upgrade w/4.10 gears 200K miles
    2005 Saturn ION-2 Stock 265K miles
    1982 Bronco, 1993 Bronco (sold), 1971 M35A2 Deuce and a Half



    There are 10 kinds of people, those who understand binary, and those who dont...

    Remember kids, the only difference between screwing around and science is writing it down- Adam Savage

  3. #3

    Default

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

  4. #4
    Sr. Engineer
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    Default

    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.

  5. #5

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

  6. #6
    Sr. Engineer
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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.

    Click image for larger version. 

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    Click image for larger version. 

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    This picture is from the back, there are two fuel lines and the hose in between them goes over to the MAP sensor.
    Click image for larger version. 

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    Click image for larger version. 

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    This is from the back of the TBI also, just from the driver's side of it.
    Click image for larger version. 

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    That is the MAP sensor I believe that the hose on the back goes into.
    Click image for larger version. 

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    Hope this helps you.
    Let me know if something else is needed.

  7. #7

    Default

    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!

  8. #8
    Sr. Engineer
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    Default

    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. :(

  9. #9

    Default

    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.

  10. #10
    Sr. Engineer
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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.

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