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Vacuum lines and Emissions

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  • #31
    Originally posted by maybeadinosaur
    I'm replacing the rotting and missing hoses on my 88 GW (amc 360) and have been able to navigate most diagrams until today. I've hit a few spots where I'm not getting clear info or I'm just unsure.

    The forum isn't being friendly with my photos so I've posted a few pics here:

    If you have any idea where I need to go from here or have access to a clear(er) diagram, I'd appreciate it! Happy new year!

    P.S. I've seen several posts where people recommend bypassing emissions/leaving off certain hoses. I prefer to have everything in place as manufactured but I'd be interested in practical reasons for leaving anything off, and which specific hoses.
    I am right in the middle of doing the same thing with my '88 - I have the chart which I am going to laminate so I can tape it somewhere on the engine bay and go after each circuit, circuit by circuit. I pulled everything recently to completely clean and repaint intake and valve covers. I noted many decomposed and dry rotted vac lines sections. Purchased VAC line from Napa (will still need more it seems) and "T's" and Unions. Carb is soaking, Pinesol is the bomb, 50/50 solution) and will soda blast before carb goes back on. I also rewrapped that section of harness that runs above exhaust manifold with silicon tape and will cover with new loom cover, should clean up nicely. Your post is so timely! Thanks, might be able to help you once I get underway. in the next week, cleaning things up takes up time but once done,it is so much easier to spot issues that pop up. My EGR was removed and checked and appears to be in great shape after cleaning, PCV I just replaced - These emission systems are complex, but do-able if you are methodical in your approach and there are some great contributors and sources on this site.

    '88 GW Sterling Silver Metallic
    Previously 1987 GW


    • #32
      That's a good idea. Also make sure you trace your EVAP lines from the can all the way back to the gas tank.

      When I was rebuilding my vacuum system (79, California emissions 360), I could not find a complete diagram anywhere. So What I did is unhook everything (and I mean EVERYTHING) and got it running smoothly to verify no leaks. Then I used all the documentation I could find to slowly hook things back together. Hook up the timing signal. Then the brake booster. then the EVAP system. Then Cruise. Then Quadratrac and heater motors. etc. I got through CA smog inspection 3 times doing this.
      79 Cherokee Chief (SOLD, goodbye old buddy)
      (Cherokee Build Thread)
      11 Nissan Pathfinder Silver Edition 4x4
      09 Mazdaspeed3 Grand Touring
      00 Baby Cherokee


      • #33
        Here is a video series identifying all components and explaining what each does, which someone may find helpful:

        Vacuum Line Replacement, Part 1 of 3- Overview and Identification of Components

        Vacuum Line replacement, Part 2 of 3- Removing vacuum lines and components from a 1987 Jeep J-20

        Vacuum Line Replacement, Part 3 of 3- Rebuilding the ignition vacuum-advance harness on a 1987 J-20
        1987 J-20
        Video projects for my J-20 on Youtube


        • #34
          Bob, those videos are great, thanks!


          • #35
            Originally posted by crisd
            Bob, those videos are great, thanks!
            You're welcome! They're excruciatingly detailed, and of no entertainment value whatsoever, but I do hope the details help someone get his truck back in order.
            1987 J-20
            Video projects for my J-20 on Youtube