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  • wmmulvey
    Senior Member
    • Apr 2011
    • 74
    #1

    No Power

    Hey all,

    Had a start up problem with a late model A-4 this spring which I solved.

    Could not get the engine to run. Traced it down to a clogged gas tank and a gunked carb.

    Bought a new tank and filter. Removed the carb and completely cleaned w/ carb cleaner an blown out w/compressed air.

    Bought a MM carb kit and replaced all w/ new.

    Installed carb and ran engine. Started up perfectly and ran great. RPM's perfect.

    Manifold overheating...290 degrees +. I took the manifold problem to this site and most agreed I had a gunked up water passage.

    Removed manifold, cleaned it out following MM instructions. Popped the freeze plugs and cleaned more. Power flushed. Pressure tested. OK

    Installed manifold.

    Ran engine. Manifold fine, no overheating. Exhaust fine.

    My new problem is that when I increase throttle It does nothing, just stays at idle.

    I did not do anything to the carb except remove and put back on w/new gasket.

    Any help please.

    Regards

    Bill
    Tags: None
  • Mo
    Afourian MVP
    • Jun 2007
    • 4519
    #2
    compression test

    Sounds like you may have a blocked main jet. Dave Neptune is a carb guru for sure...he might be able to tell you exactly what's going on there.


    Now for another thought...this will only pertain if you know it's getting lots of fuel....but here goes. From what I understand your engine overheated...is that correct? Earlier this year I was working on an engine and it ran fine idling and rev'd idling. It made some effort in reverse and would bog and stall in forward. Turned out to be a head gasket failure (he showed me a pic that had his valves out as well)....I had done the compression test with the thumb and thought all was good. Later that week he got a compression gauge and had low compression on 2 adjacent cylinders...indicative of head gasket failure. It had enough compression to start but not enough for a few horsies. Should it turn out to be NOT a fuel supply problem, I would recommend a compression test with a gauge and see what you come up with.
    Last edited by Mo; 08-22-2012, 04:21 PM.
    Mo

    "Odyssey"
    1976 C&C 30 MKI

    The pessimist complains about the wind.
    The optimist expects it to change.
    The realist adjusts the sails.
    ...Sir William Arthur Ward.

    Comment

    • Dave Neptune
      Afourian MVP, Professor Emeritus
      • Jan 2007
      • 5050
      #3
      Fwiw

      Bill, Mo has some great thoughts and I can't add to much to it.

      But one thing does come to mind if you mean nothing happens when moving the throttle, not even dying points to the cable may not be hooked up. I've seen that happen more than once.

      Dave Neptune

      Comment

      • ILikeRust
        Afourian MVP
        • Sep 2010
        • 2212
        #4
        Dave beat me to it - check to make sure you didn't accidentally unhook the throttle cable when removing and reinstalling the carb.
        - Bill T.
        - Richmond, VA

        Relentless pursuer of lost causes

        Comment

        • ndutton
          Afourian MVP
          • May 2009
          • 9776
          #5
          Originally posted by ILikeRust View Post
          Dave beat me to it - check to make sure you didn't accidentally unhook the throttle cable when removing and reinstalling the carb.
          That's end or sheath and it applies to both ends equally. Give a thorough examination, assume nothing.
          Neil
          1977 Catalina 30
          San Pedro, California
          prior boats 1987 Westsail 32, 1970 Catalina 22
          Had my hands in a few others

          Comment

          • 67c&ccorv
            Afourian MVP
            • Dec 2008
            • 1592
            #6
            Carb linkage IMO.

            Comment

            • wmmulvey
              Senior Member
              • Apr 2011
              • 74
              #7
              Originally posted by 67c&ccorv View Post
              Carb linkage IMO.

              In answer to all your appreciated replys.

              Engine did not overheat, just the manifold.

              Compression perfect, wet & dry w/gauge

              Throttle cable not attached. Increased throttle by hand.

              In re-thinking the prob last night I also thought of the main jet clogged. But why? New gas tank, new gas lines, new filter.

              I don't know much about the mechanical fuel pump but thinking maybe the sediment bowl is gunked and sent some junk to the carb.

              How do I remove the bowl?

              Also I have a slight leak in my muffler. It does not leak when the engine is running but when I shut the engine down the residual water left in the muffler will drip out.

              I don't think that we be causing problem.

              Regards

              Bill

              Comment

              • ndutton
                Afourian MVP
                • May 2009
                • 9776
                #8
                I would think opening the throttle with a clogged jet would push the mix way lean to the point of instant stalling which is not the case.

                My wild guesses:
                • Try the same thing with the flame arrestor removed and see if there's a difference.
                • Failing that I'd pull the carb again and look for proper butterfly operation when the throttle lever is moved.
                Neil
                1977 Catalina 30
                San Pedro, California
                prior boats 1987 Westsail 32, 1970 Catalina 22
                Had my hands in a few others

                Comment

                • Dave Neptune
                  Afourian MVP, Professor Emeritus
                  • Jan 2007
                  • 5050
                  #9
                  Sure

                  Bill, if you just replaced the gasket and nothing else leads me to this. If you are opening the throttle something has to happen as more air/fuel should be sucked in. Are youu sure your not moving the choke instead? Even if the choke is closed and the flame arrestor was plugged moving the throttle should do something.

                  Dave Neptune

                  Comment

                  • Dave Neptune
                    Afourian MVP, Professor Emeritus
                    • Jan 2007
                    • 5050
                    #10
                    Another thought

                    Bill, did you perhaps leave a rag or something in the manifold? If it was plugged enough to idle and nothing more then the throttle would have little affect but the mix would change as the butterfly moved past the idle ports.

                    Dave Neptune

                    Comment

                    • wmmulvey
                      Senior Member
                      • Apr 2011
                      • 74
                      #11
                      Originally posted by Dave Neptune View Post
                      Bill, did you perhaps leave a rag or something in the manifold? If it was plugged enough to idle and nothing more then the throttle would have little affect but the mix would change as the butterfly moved past the idle ports.

                      Dave Neptune
                      Planning on getting to the boat early next week. I will post again.

                      Regards

                      Bill

                      Comment

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