Announcement Announcement Module
Collapse
No announcement yet.
What clogs the idle tubes? Page Title Module
Move Remove Collapse
X
Conversation Detail Module
Collapse
  • Filter
  • Time
  • Show
Clear All
new posts

  • What clogs the idle tubes?

    Greetings. My question is “where is the stuff coming from that clogs the idle tubes on my Carter carb ?” I’ve searched the best I can and find lots of info relative to the symptoms and how to help by drilling out the tubes, but where does the stuff come from? I realize the popular solution is to just get rid of the thing, but it’s one of those things that just pisses me off that I can’t make it work! It works perfect for about 300 miles and then starts the ol’ rough idle thing, I pull the tube cluster, clean the tubes, and she’s back to running smooth.

    Here’s what I have: ‘83 CJ7, 258, carter BDD, Nuttered, TFI ignition. The only vaccum I’m using is the dizzy advance, choke, EGR, Evap can, and PCV. I currently have the PVC inlet removed from the breather housing with a filter attached to the hose, trying to eliminate oil blow-by into the breather. Pulse air stuff is also gone. I have installed a pre-filter just before the stock fuel filter at the carburetor.

    I have not dropped the fuel tank which seems like the next thing to do, but if that were the problem, why would “Jeep” have recommended drilling the idle tubes to help the problem if replacing the fuel tank would fix it?

    I just hate to be beat by some goo in some little tubes!

    What is this stuff and where does it come from?

  • #2
    Years ago I was having problems with mine, it was crap out of the new fuel filters clogging them up. I put an in line fuel filter in between the carb and the stock fuel filter. Still run this setup but now I have the third filter in the front of the MC 2150, I need to take the inline filter out now.

    Comment


    • #3
      gper,
      Thanks for the reply. Like you, I thought an additional filter might help. I installed one in front of the stock filter about 600 miles ago. I still have to clean the tubes after 300 miles or so.

      You said stuff was coming from the new filters. Do you mean the filter was bad and coming apart, or the contaminants were just passing through the filter somehow?

      Also, are you saying you have a similar problem with the Motorcraft carb?

      Comment


      • #4
        Welcome to the forums, hooked!! I dropped the tanks on both my '80 & '84, you would be suprised at the junk in there!! One of the biggest problems I had was using my older gerry-cans. I would siphon the gas into the Jeep, along with the paint chips, dirt, etc. that as in the can. The '84 I dropped when I rebuilt the carb. It was pretty nasty to, though I had just bought it and don't know if the PO had ever siphoned gas in. Anyway, when I rebuilt the carb, the bowl was full of nasty crud, so if you haven't pulled the carb apart and cleaned it, chances are the stuff is coming from the bowl on the carb. Once I cleaned the tank and rebiult the carb along w/ a fresh filter, I haven't had any problems. Just a couple of thoughts. Good Luck!!

        Comment


        • #5
          thanks for the thoughts Hill, Bill E,

          Guess I just keep avoiding dropping the tank. I don't know, like yourself, what my PO's fueling habits were. Did you replace the tank or clean it somehow?

          I was hoping that by adding the additional fuel filter in-line a few weeks ago that it would catch the stuff before entering the carb but its just not doing it.

          When I started I could only go maybe 100 mile before having to clean the idle tubes. I think getting rid of the "Pulse Air System" helped. I was getting some blowback into the air filter assembly.

          It still seems funny to me that Jeep would have recommended drilling the idle tubes out larger to help the problem if the real problem was dirty fuel. Why didn't they just recommend a new gas tank?

          thank again for the thoughts.

          Comment


          • #6
            i was having similar problems with my '85 CJ-7 and it turned out that the air tubes were allowing exaust to back up into the carb...it was throwin rust from my cat 9and the air tubes themselves) into my carb(s) and trashin em up...i figured it out when i was lookin at my carb, leaned over, grabbed the air tube on that side and it broke off in my hand, lol...ive since plugged em both off and my girls runnin great

            Comment


            • #7
              Originally posted by hookedoncj7
              gper,
              Thanks for the reply. Like you, I thought an additional filter might help. I installed one in front of the stock filter about 600 miles ago. I still have to clean the tubes after 300 miles or so.

              You said stuff was coming from the new filters. Do you mean the filter was bad and coming apart, or the contaminants were just passing through the filter somehow?

              Also, are you saying you have a similar problem with the Motorcraft carb?
              I have no problems with my MC 2150 I had one new filter that had some slivers of the filter paper on the outlet side of the new filter. They plugged the carb up so the screen filter went between the new stock fuel filter and the carb.

              Comment


              • #8
                better fuel filter?

                Thanks GPER, understand what you're saying now. Glad to hear the MC carb is doing well for you because that's where I plan to go when I finally get tired of tinkering with the Carter carb.


                Captain I think the air tubes you mentioned are the "Pulse Air" tubes I mentioned earlier. I think what happens is the check valve or a vac leak can cause a malfunction in the system and allow the air to go backward back into the air filter assembly. Rust inside the tubes at the air filter and inside the air filter housing air the signs of problem. That's why I removed mine. It is a key part of the emmision system though, so anyone should take note of that before removing. I don't believe there is any performance advantage to removing it if it is working properly.

                Do you guys think there might be a different type of fuel filter that would be better at catching this mystery goo before entering carb than the stock filter?

                Comment


                • #9
                  cleaning tank

                  Hey hooked, I cleaned my tank(it's the 20 gal factory, plastic tank), I pressure washed it, then let it air dry, then I washed (sloshed it?) w/1/2 gal gasoline and put in some isopropel in case of any water leftover. I originally dropped the tank during my frame off resto, while checking the sending unit I noticed the pick-up screen was missing. It was in the tank, not doin' any good!

                  As far as Jeep saying to drill out the tubes, maybe thier line of thinking was the bigger tubes would pass the stuff clogging it?? I heard they recanted that fix though, so maybe it didn't work so well. I left mine as they were, not sure if they are stock or reamed. I am running a carter, but it's not the bbd(no 5 wire connection) although thats the only difference. The rebuild kit for the bbd worked fine. Good Luck, the carters are touchy, but if you get it dialed in, they work good.

                  Comment


                  • #10
                    By the way..............

                    I also removed the pulse air setup, same reason as the captain.

                    Comment


                    • #11
                      After so many problems with several carter rebuilds I went to the Howell TBI and never looked back dumped all of the furd crap and tubing out of my 83 cj that was legal in CA got 18 mpg.

                      Comment


                      • #12
                        yep...those air tubes ruined my day more than once...i need a new exhaust system (rooter to the tooter), and im considering putting the air tubes back in effect, along with the EGR...but i dont see the valves and such for sale anywhere...she's running great now though so im kinda leaning torward getting the older model pipe (from the header to the muffler), don't know if it fits though (i dont see why not)...i alos took my PCV to manifold line and spliced the canister purge into it...the pressure seemed a bit high to me and it seems to work fine like that...but i gotta say...i was on here for 4 days and my jeep went from crap to the Shizz (to me anyway)...so good luck man, you get her purrin' in no time

                        Comment


                        • #13
                          thanks for all the comments guys.

                          Fuel injection is for sure on my wish list, maybe someday the funds will be there for it. I think the MC2100 is more in my budget range.

                          Anyway, I think you guys have helped me decide what I thought was the problem all along with the clogged idle tubes. I'm gonna go ahead and drop the tank and check it out and replace it if needed. Might as well get the gas gauge working while I'm at it.

                          It would be nice to get past the carb issue and finish some of the other things on the Jeep.

                          I did pretty much finish the fab work on my front winch bumper this
                          weekend and finally installed my new one piece axles in the AMC 20 last week though.

                          I guess we never get done do we?

                          Comment

                          Working...
                          X