Rebuilt Thermoquad issue -- It has to be primed before start each time

Discussion in 'Fuel and Air Systems' started by purplehazenils, Jun 13, 2018.

  1. purplehazenils

    purplehazenils Well-Known Member

    Messages:
    210
    Likes Received:
    32
    Joined:
    Aug 11, 2013
    Location:
    Sweden
    Local Time:
    2:26 PM
    -----The rebuild:-----
    So I rebuilt my Thermoquad a while back, the main well O-rings/X-rings were bad but I bought a whole kit to to change out other gaskets etc while I was at it.

    I did the rebuild to about 85%, I didnt disassemble absolutely everything but I changed the main gaskets, rings, accelerator pump and some other stuff. I also did the adjustments to spec, it wasnt that far off to begin with.

    ----- The problem: -----
    I cant remember if it was a problem from the start or if it happened a few days after use ... Anyway, the car runs and drives fine but you have to prime the engine/carburetor before you start it each time. Sometimes it will start without priming but if it dies when you put it in gear you have to prime it to get it going again.

    I noticed that the two nozzles in the primaries which squirt fuel when you pump the carb dont squirt fuel anymore so I assume this is the problem. But what should I be looking for when I disassemble again? A somehow jammed accelerator pump?
     
  2. brian6pac

    brian6pac Well-Known Member

    Messages:
    2,483
    Likes Received:
    1139
    Joined:
    Nov 15, 2016
    Location:
    N.E.Ohio
    Local Time:
    9:26 AM
    Did you put the check valve back in under the squirter nozzles
     
  3. pishta

    pishta I know I'm right....

    Messages:
    12,456
    Likes Received:
    2446
    Joined:
    Oct 13, 2004
    Location:
    Tustin, CA
    View My Photos
    Local Time:
    6:26 AM
    there is a dinky tube that feeds the squirters from the pump well, it may have come off or become clogged. remove shooter and pump carb to see if anything comes out.
    Pic06.jpg
     
    • Thanks! Thanks! x 1
    • Agree Agree x 1
    • purplehazenils

      purplehazenils Well-Known Member

      Messages:
      210
      Likes Received:
      32
      Joined:
      Aug 11, 2013
      Location:
      Sweden
      Local Time:
      2:26 PM
      Hmmm ...what do they look like?
       
    • purplehazenils

      purplehazenils Well-Known Member

      Messages:
      210
      Likes Received:
      32
      Joined:
      Aug 11, 2013
      Location:
      Sweden
      Local Time:
      2:26 PM
      Good point that would cause it right? The nozzles are fed from the accelerator pump which is fed from that hose?
      I replaced the hose with a new one, it was one snug but who knows if it came off somehow..?
       
    • RustyRatRod

      RustyRatRod Just another dumbass. FABO Gold Member Technical Editor

      Messages:
      45,738
      Likes Received:
      9785
      Joined:
      Jun 7, 2010
      Location:
      Georgia
      View My Photos
      Local Time:
      9:26 AM
      You seem unfamiliar with what you did to the carburetor even by your own standards, so trying to get help from us here is going to be difficult. You don't seem to even know what the accelerator squirter check valve is, we have no way to know if you removed it, or put it back......or even if it was there to begin with. Thermoquads can give even a seasoned professional a tough time, so they can and will give a novice hell.

      I mean no offense by any of this, just trying to get you to understand, coming on here saying "hay guys, I sorta half way rebuilt my carburetor, now what's wrong?" is going to be difficult at best. And it's not like we have a member here conveniently located to come help you in Sweden.

      If you could be a little more clear about what specifically you did and did not do, that would be a start.
       
      • Thanks! Thanks! x 1
      • Agree Agree x 1
      • MoparLeo

        MoparLeo NRA PATRON LEVEL LIFE MEMBER FABO Gold Member

        Messages:
        245
        Likes Received:
        104
        Joined:
        Feb 10, 2016
        Location:
        Moreno Valley, Cal. So. Cal.
        Local Time:
        6:26 AM
        Do you use a rebuild instruction sheet? It would show where and what the parts are. I'll bet the accelerator pump feed tube is damaged or disconnected.
         
      • purplehazenils

        purplehazenils Well-Known Member

        Messages:
        210
        Likes Received:
        32
        Joined:
        Aug 11, 2013
        Location:
        Sweden
        Local Time:
        2:26 PM
        Yeah your right I have absolutely no idea what an accelerator squirter check valve is. If you google "accelerator squirter check valve thermoquad" you get nothing and its not that easy to find out.
        Its not easy to help me either because Im not sure what anything is called. But symptoms can sometimes be linked to causes or areas at least.
        Thats how I found out what was wrong with the carb in the first place I said hey my Thermoquad is all rich or something, someone mentioned o-rings/x-rings which was a huge help because I checked them and they were crap and the cause.
        Like from this thread so far I have had my "suspicion" that this has something to do with the accelerator pump verified and got the tip to check the pipe that feeds it. I know what area to look at now :)
         
      • purplehazenils

        purplehazenils Well-Known Member

        Messages:
        210
        Likes Received:
        32
        Joined:
        Aug 11, 2013
        Location:
        Sweden
        Local Time:
        2:26 PM
        Yes I did, will check on that when I get access to it.
         
      • Bulldozer

        Bulldozer a.k.a. 73AbodEE

        Messages:
        15,438
        Likes Received:
        1531
        Joined:
        Oct 16, 2011
        Location:
        up the street
        Local Time:
        8:26 AM
        I'm fore warning you right now , if you have to prime it first , one of these times it will backfire and very possibly catch your car on fire , I know first hand. I've had firebog. make sure you have the air cleaner on or a fire extinguisher handy. get it fixed right.
         
      • BigBlockMopar

        BigBlockMopar BigBlockMember

        Messages:
        1,429
        Likes Received:
        391
        Joined:
        May 1, 2011
        Location:
        Netherlands
        Local Time:
        3:26 PM
        A common issue with the Thermoquad plastic housings is the 2 little 'oilpans' / buckets at the bottom start leaking and let fuel drain from the float chambers straight into the manifold.
        The fix is to crack them loose and reattach them with JB-Weld or something like that.

        Pic07.jpg
         
        • Thanks! Thanks! x 1
        • Agree Agree x 1
        • purplehazenils

          purplehazenils Well-Known Member

          Messages:
          210
          Likes Received:
          32
          Joined:
          Aug 11, 2013
          Location:
          Sweden
          Local Time:
          2:26 PM
          Naturally with my luck I had to do that, they were leaking baddd :eek:

          DSC_1258.JPG

          DSC_1261.JPG
           
        • purplehazenils

          purplehazenils Well-Known Member

          Messages:
          210
          Likes Received:
          32
          Joined:
          Aug 11, 2013
          Location:
          Sweden
          Local Time:
          2:26 PM
          Damn it never crossed my mind.. Thanks for the tip!
           
          • Like Like x 1
          • brian6pac

            brian6pac Well-Known Member

            Messages:
            2,483
            Likes Received:
            1139
            Joined:
            Nov 15, 2016
            Location:
            N.E.Ohio
            Local Time:
            9:26 AM

            part # 76 thq.gif
             
          • pishta

            pishta I know I'm right....

            Messages:
            12,456
            Likes Received:
            2446
            Joined:
            Oct 13, 2004
            Location:
            Tustin, CA
            View My Photos
            Local Time:
            6:26 AM
            76 is going to look like a little pointed pellet: the point goes down. It prevents the discharge tube from draining between squirts and also prevents the air stream from pulling fuel out the squirter at high engine speed. If your missing it, it wont give you an immediate shot as it will allow air to be drawn into the pump circuit when it "reloads" but it will still give you a shot.
             
          • rumblefish360

            rumblefish360 so close yet so far away

            Messages:
            31,597
            Likes Received:
            3939
            Joined:
            Jun 21, 2005
            Location:
            New York, on a Island
            View My Photos
            Local Time:
            9:26 AM
            Get a book titled,
            “How to Rebuild Carter/Edelbrock carbs”
             
          • AJ/FormS

            AJ/FormS 367 FormS clone 3.09-1.92-1.40-1.09-.78od 3.55s

            Messages:
            13,439
            Likes Received:
            3160
            Joined:
            Jan 19, 2014
            Location:
            South-Central Manitoba,Canada, 900ftelevation
            View My Photos
            Local Time:
            8:26 AM
            Yeah but the first 20/30% is gonna be an air shot,lol.
             
          • AJ/FormS

            AJ/FormS 367 FormS clone 3.09-1.92-1.40-1.09-.78od 3.55s

            Messages:
            13,439
            Likes Received:
            3160
            Joined:
            Jan 19, 2014
            Location:
            South-Central Manitoba,Canada, 900ftelevation
            View My Photos
            Local Time:
            8:26 AM
            Hang on guys, these are two different problems yet the source may be the same.

            The car runs and drives fine say the pump circuit works once the bowls are full.
            The second part is actually the problem; where is the gas draining to, at shut down. My guess is those little pans are not sealed, and the gas went into the intake, and you know where it goes from there. This also explains #3, it dies when you put it into gear.

            I doubt you can seal those pans by globbing JB on the outside. Like previous poster BigBlockMopar said, " you have to crack them loose" and put the sealer where it needs to be. Then test them before you put it all back together. Actually since you have already applied the JB, take the bowl off and test it; Yes with gas, or alcohol.
             
            Last edited: Jun 14, 2018
          • purplehazenils

            purplehazenils Well-Known Member

            Messages:
            210
            Likes Received:
            32
            Joined:
            Aug 11, 2013
            Location:
            Sweden
            Local Time:
            2:26 PM
            1. Squirter Nozzle
            I never actually removed it during the "rebuild" but I checked and it was in place. With mouth i could blow air though the hose so it exited though the nozzles in the primaries but couldn't suck air back. Pic. 1

            2. Tube
            Was not damaged, disconnected or clogged Pic.2

            3. Mini "oil pans" for fuel
            Well spotted AJ/FormS, I did not break them off I just globbed fuel on the outside after roughing up the surface with a dremel.
            I dried everything up, filled them with gasoline and waited 15 minutes but not a drop of moisture came through Pic. 3

            Anything I could have missed? :realcrazy:

            DSC_1385.JPG

            DSC_1386.JPG

            DSC_1387.JPG
             
            Last edited: Jun 14, 2018
          • purplehazenils

            purplehazenils Well-Known Member

            Messages:
            210
            Likes Received:
            32
            Joined:
            Aug 11, 2013
            Location:
            Sweden
            Local Time:
            2:26 PM
            Which is the shooter? The pump nozzle assembly?
             
          • AJ/FormS

            AJ/FormS 367 FormS clone 3.09-1.92-1.40-1.09-.78od 3.55s

            Messages:
            13,439
            Likes Received:
            3160
            Joined:
            Jan 19, 2014
            Location:
            South-Central Manitoba,Canada, 900ftelevation
            View My Photos
            Local Time:
            8:26 AM
            Cracked bowl then?
            There's only supposed to be a few ways out of the bowls; UP the main wells, and UP the pump circuit.
            You seem to have them covered.
            I suppose you could fill the bowls, and watch for fuel escaping somewhere that it shouldn't be. But it's tricky cuz at 70plus degrees, the fuel flashes away pretty fast. I think I'd try it with solvent,mineral spirits or paint thinner, or even diesel. Yeah diesel; it will leave a tell-tale greasy surface behind. Keep the liquid level to about 1/2"below the top of the bowls, cuz diesel will climb up the sides,by what I think is called capillary action.
            So will the other fuels but they will evaporate before climbing over the side. Diesel is way slower to evaporate, so it will climb over if the level is too high, and of course that would give you a false sign. Diesel will also be slower to migrate thru a crack, so give it an hour or so.
             
            Last edited: Jun 14, 2018
            • Thanks! Thanks! x 1
            • AJ/FormS

              AJ/FormS 367 FormS clone 3.09-1.92-1.40-1.09-.78od 3.55s

              Messages:
              13,439
              Likes Received:
              3160
              Joined:
              Jan 19, 2014
              Location:
              South-Central Manitoba,Canada, 900ftelevation
              View My Photos
              Local Time:
              8:26 AM
              Yes, the parts you have indicated there,in post #19. Squirter, shooter, nozzles ; all same part.
               
            • purplehazenils

              purplehazenils Well-Known Member

              Messages:
              210
              Likes Received:
              32
              Joined:
              Aug 11, 2013
              Location:
              Sweden
              Local Time:
              2:26 PM
              Cool, I filled the "fuel oil pans" and the bowls with diesel this time just enough so it wont climb the walls. Going to leave it overnight and see if anything comes through. The whole plastic resin part looks very good, couldn't fins any cracks anywhere..
               
            • AJ/FormS

              AJ/FormS 367 FormS clone 3.09-1.92-1.40-1.09-.78od 3.55s

              Messages:
              13,439
              Likes Received:
              3160
              Joined:
              Jan 19, 2014
              Location:
              South-Central Manitoba,Canada, 900ftelevation
              View My Photos
              Local Time:
              8:26 AM
              If only the oilpans are full, then your test will only prove the oilpans. I was suggesting you fill the entire float-bowl chamber. Oh nevermind I reread your post, and noticed the "and the bowls" this time
              The oilpans themselves I would test with gas. This will give almost instant results.You'll see the JB turn color and change it's sheen, as it become moist.

              Here's another test I just dreamed up; I have never done it. You should be able to invert the black body and submerge it in a pail of water, and if there is a crack, I wonder if the trapped air inside wouldn't find it and bubble out.
               
              Last edited: Jun 15, 2018
            • BigBlockMopar

              BigBlockMopar BigBlockMember

              Messages:
              1,429
              Likes Received:
              391
              Joined:
              May 1, 2011
              Location:
              Netherlands
              Local Time:
              3:26 PM
              I once had a bad case of this Thermoquad fuel 'oilpan' leakage when the engine would start to idle very rich without possibility to lean it out anymore.
              When opened up shortly after, I noticed fuel in one of the chambers in the lower base plate where the these oilpans normally reside when the carb is together.
               
              Last edited: Jun 16, 2018