No announcement yet.

Vacuum lines and Emissions

  • Filter
  • Time
  • Show
Clear All
new posts

  • Vacuum lines and Emissions

    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.

  • #2
    Have you visited this site yet? Hope it helps..

    Stock '77 J10 Pioneer LWB
    360 V8, 2bl (49 state)
    T-18 4 speed
    Dana 44's


    • #3
      yes use that link and go to Nappa and buy vac tubing by the foot - you will need various sizes - a small kit of vac fittings - T pieces is not a bad idea as the old ones crack

      don't buy windshield washer tubing - it will collapse when warm
      Abort? Retry? Ignore? >

      86 GrandWag. Howell fuel Injected 360. MSD Ignition + Dizzy. 727/229 swap BJ's 2" Lift and 31's

      88 Wrangler 4.2, Howell TBI and MSD - Borla Headers w/ Cat-back + winch and 31's AND a M416 trailer (-:


      • #4
        I have the hoses and that diagram but havent been able to use it successfully to connect the parts in the pictures I've uploaded.


        • #5
          If you are going through a TON more gas than you ought to be, the round shut off valve on the air cleaner inlet in this pic needs to be jammed open or removed if it's non-functional. I went through 2 tanks of gas in a hurry in my Eagle because someone hooked it up wrong and it closed on the highway! The other lets hot air in to prevent carb icing.

          Jeep gauges are for amusement only. Any correlation between them and reality is purely coincidental.


          • #6
            Are those the two prongs on the back of the cleaner housing? If so, I don't know if it's functional so I'd like to hook up the right hoses to find out.


            • #7
              Lets do the easy ones first.

              Air Cleaner items

              1. Controls Hot/Cold air inlet door (also called flapper and many other names). TAC VAC Motor on the vacuum diagram. This vacuum motor's connecting tubing goes underneath and clips to the the air cleaner's base. It connects to TAC Temperature Sensor, a brass temperature actuated valve in the air cleaner's base.

              Circled blue plastic valve. EGR TVS in the vacuum diagram. The smaller outside nipple connects to the EGR Valve. The EGR Valve is attached to the intake manifold and has a big steel vacuum motor. Below cabureter air temperature 45 degrees F, it prevents the EGR from opening no matter what. The other side gets vacuum from a coolant temperature controlled valve, the Dual CTO.

              2. Is that the hose from the Delay Valve? That goes to a manifold Vacuum source. In the 1988 vacuum diagram this is a little confusing. The manifold vacuum represented by a circle representing a nipple in the intake manifold. From this nipple there should be a T supplying vacuum to the Brass TAC and the delay valve for the snorkel nozzle's shutoff valve. This should always be open when the engine is running. It shuts only to keeps fuel vapor from the carb bowl from evaporating to atmosphere when the engine is off.

              Evaporative Fuel Canister

              That's the purge signal line. On your '88 it should T into the line going into the EGR TVS from the Dual CTO. (Evaporative Cannistor and System operation in tech archives but I dont think you need that for what your doing)

              Dual CTO
              That looks to be a dual Temperature Control valve. In the upper right is the EGR Valve. this is a Dual DTO.
              I'm going to guess, that:
              E. Is supplied ported vacuum from the Carburator. Connect CTO's 'E' directly to the Carburetor nipple marked 'E' in the diagram. (There is no T to the carb solenoid; that's just a printing or editing loss of the white seperation. )
              D. Connect to a T. One outlet of the T goes to the EGR TVS inlet on the aircleaner. The other goes all the way up front to the purge signal cap on the vapor cannister.
              For this side of the CTO, No vacuum is supplied at idle. When the throttle is slightly to moderately open above idle, vacuum is supplied to the CTO. When the coolant is warm enough (115 F in '84, probably the same for an '88) the CTO opens allowing the ported vacuum to go to the EGR TVS and Evaperative Purge valve.

              A. Vacuum in from a manifold vacuum source. The diagram shows that manifold vacuum source in an intake runner. See what you can find.

              B. Goes all the way up front to control the air pump control valve.
              On this side of the CTO, vacuum is available at idle and slightly to moderately open throttle positions. When the CTO is warm enough, it opens and the vacuum actuates the air pump's valves.

              PS. In your first IMGUR photo the Fuel supply Hose looks small. Could just be the photo. It should be a 5/16 i.d. hose rated for Fuel. Honestly, its worth the peace of mind to use Fuel Injection rated hose. It's only alittle bit more costly and less likely to be damaged by components of pump 'gasoline' whether its ethenol or some other component.
              Last edited by nograin; 01-03-2016, 11:44 AM.
              '85 Grand Wagoneer
              360 727auto, NP229
              body by beer (PO)
              carries wood inside
              no "wood" outside
              My other car is a fish


              • #8
                Wow, thank you - that's a lot of great information! I'm limited on the time I can put into this but I'll see what I can put together from everything you've said.

                I guess I misread another diagram and previously connected the EGR via hose to the PCV valve at the front of the engine (intake?), which has another hose going to the base of the carb. You can see the hose in the first picture, behind the red line. When I connected this, a bit of black smoke (looks like carbon build up) puffed out and still does, only on start up. Is this doing any harm?


                • #9
                  PCV valve is behind the carburator, so I can't even guess what you've hooked the EGR to!? edit: Looking at your photo on imgur, if you mean the EGR is hooked to the center nipple on the front of the carb, very low, that's the Power Valve. You need to get manifold vacuum to your power valve, or it will be way too lean at wide open throttle, and that could be bad. For quick fix you can Tee into that manifold vac fitting with the orange hose on it if you have to for now. That's how it was done in '85. Your '88 is a little different, for some reason Teeing into the line going to the vacuum resevoir from the rear manifold vac fitting. For the EGR, Short hose to the blue plastic, a short hose from the plastic to CTO. Short hose to manifold vacuum source. If you're going crazy trying to keep things straight, buy a set of colored electrical tape and color code your lines.

                  PCV Valve goes in between that 3/8" OD elbow coming out of the intake manifold behind the number 8 runner, and the back of the carb's base. There is a T on the side of the PCV valve. That's a small hose going to the charcoal canister. (Yes its manifold vacuum). The elbow goes into the valley where oily vapor and blowby builds up and can reduce efficiency.

                  It's a big puzzle. Have fun with it even though it can be frustrating at times.

                  edit 2: Here's a couple of photos that should help.
                  Front view of a 2150 showing the three vacuum connections.
                  E is a ported vacuum source for the Emmissions EGR
                  S is another ported vacuum source, but used for the Spark Timing (that is distributor vacuum advance)
                  Power Valve requires manifold vacuum to stay closed.

                  Driver Side View.
                  PCV valve connects by a molded S shaped hose to the elbow - although maybe 88 is different. A regular hose will kink, but will get you by until you get the correct one.
                  EGR TAC Connector is circled. You probably can get by pushing the hoses directly on.
                  TAC Temp Sens hose is below the circled EGR TAC Connector. It attaches to the brass temperature switch in the bottom of the air cleaner. There's a small check valve in that line. Follow it down behind and below the PCV Valve to the manifold vacuum fitting. Yours will need a Tee in this hose.
                  On Far left, the yellowed plastic can with a bit of foil on it, is the Non-Linear Valve. (NLVR)

                  Ristow has really good photos of a 2150 carburetor off the engine where you can see all the connections. Go to the Tech Archives Engine Subforum. Change the preferences in the lower left to show all threads from begining instead of just the past month. Then you'll see the 2150 Rebuild thread.
                  Last edited by nograin; 01-03-2016, 11:16 PM.
                  '85 Grand Wagoneer
                  360 727auto, NP229
                  body by beer (PO)
                  carries wood inside
                  no "wood" outside
                  My other car is a fish


                  • #10
                    Nograin's description of the 5-port Dual CTO (coolant temperature override) switch connections is exactly right.

                    I would just add that the 5-port valve is normally connected to the corresponding lines by a 5-port rubber fitting. Not completely necessary, but nice to have.

                    You can see the fitting here in this picture someone nicely posted:

                    Worth mentioning is the fact that the port marked "C" in your photo is open to atmosphere through a filter, hence the boxed "F" in the diagram.

                    The filter material is clearly seen in the photo linked above.
                    1962 Willys Station Wagon
                    1989 Grand Wagoneer


                    • #11
                      Ok Im going to try and jump on this beast today. I do want to point out, though, that the PCV valve previously mention and clarified has a twin on the front of the engine I believe I tried routing based on the first image here:

                      With that said - once properly connecting everything on the CTO, I don't have an idea of what to do with the valve on the front of the engine or the yellow line in pic 1 (yet).

                      Edit: Also, ty grandjeeper - id love to use a fitting but search results haven't returned anything so I may be out of luck on that.
                      Last edited by maybeadinosaur; 01-06-2016, 03:45 PM.


                      • #12
                        Originally posted by maybeadinosaur

                        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.
                        Only items to keep are EGR & vapor can, all the other crap can go.
                        Being in CA both mine are this way and pass emissions with flying colors.
                        Although they are both fuel injected, same can be done with a carb.
                        A nice modern 3-way Catalytic converter is far superior in reducing emissions than the craptastic OE Cat, and doesn't require air injection.

                        None of the junk is needed, and they don't run "better" with it all working/intact. It was all a band-aid/after thought due to EPA restrictions @ time.

                        If you live in a cold climate, might want to keep the air cleaner flappers/heat stove in place for cold starts.
                        88 GW, 67 J3000, 07 Magnum SRT8


                        • #13
                          After removing the cleaner housing, i found these 2 coming from the manifold - is they just capped? I didn't want to start yanking without checking.


                          Also, theres a larger port/pipe which you can see on the left. It has a cap on it but I'm not sure what this is. Leaving it alone for now but if you have an idea, that'd help!

                          Edit/Update: I've removed the caps and connected all but 2 lines on from the CTO. I've also replaced my fuel line and reconnected everything on the air cleaner housing. I'm left with 2 lines missing, though: What I labeled B and E.

                          B - I can't find the air pump or air control valve - where should I be looking?

                          E - The E valve on the carb is connected directly to the distributor. After looking at this diagram, it looks like I'm overlooking something or parts were removed:

                          Should I just T into the valve? I'm not able to find/see an air pump, air control valve, or the HDC CTO - could these have been removed or am I just missing it?

                          Also, the power valve is now free and connected to nothing and what I previously though to be the PCV seems to be #8 on that diagram, with nothing hooked up to it.
                          Last edited by maybeadinosaur; 01-06-2016, 04:09 PM.


                          • #14
                            Also, I lost the cap on the large port in the recent photo. Trying to figure out what that is.


                            • #15
                              Here's the best info I have found on figuring out vacuum and emissions systems.


                              Also, at the bottom of that, there is a header called 'Simplification' and tells you how to eliminate some things if you're interested in that.
                              (*Allowed to post while failed 'I am not a Bot' test results are under appeal)

                              My build thread: 1982 Cherokee Laredo

                              Ristow's Bunker

                              Member, FSJ Prissy Restoration Association