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1989 Johnson 225 need to clean idle circuit

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  • 1989 Johnson 225 need to clean idle circuit

    My 225 with in tact VRO starts and runs awesome. Cruises around 3500 rpms at @30 mph..depending on head wind. When I start the boat cold I get a very rough idle. The engine runs, but shakes as if its struggling to maintain. As soon as the engine warms up...she idles and holes hots just great. Any ideas what I can look at? Asked a local mechanic, but so far they are swamped with summer work.
    1982 Whaler Montauk 90HP( sold)[br]1977 25 Mako CC 225HP

  • #2
    Does it smooth out at all if you hit the choke/purge solenoid to give it more fuel? A cold engine needs a Rich fuel condition. The carbs are jetted for operating temp (Leaner condition). That's why fuel injection is nice, AFR is adjusted based on multiple variables.

    Also, try pumping the primer bulb as it's idling rough when cold. Since it idles nicely when warm leads me to believe its not the carbs.
    [br]Michael R. Delgado[br]1972 Mako 22[br]http://classicmako.com/forum/topic.asp?TOPIC_ID=15745[br]1976 Mako 25[br]http://classicmako.com/forum/topic.asp?TOPIC_ID=18013&SearchTerms=mako,25[br]

    Comment


    • #3
      Also take a look at the impeller and maybe gear oil. If you have something putting additional strain on engine while its trying to idle cold, it could cause it to stumble. When the gear oil or impeller heats up, less resistance so no stumble. You could drop lower unit and see how it starts/idles cold to rule out these two things.

      I agree if it runs ok at idle when its warm, not likely the carbs.

      Comment


      • #4
        Yes the motor purrs after the it warms up...in and out of gear at 8-900 rpms and never misses a beat.

        The choke is built into the key control. You push in when starting to choke. Not sure you can push in when already running, but will try. Primer bulb gets rock hard on prime, but i can certainly try that.
        quote:


        Originally posted by mrdelgado


        Does it smooth out at all if you hit the choke/purge solenoid to give it more fuel? A cold engine needs a Rich fuel condition. The carbs are jetted for operating temp (Leaner condition). That's why fuel injection is nice, AFR is adjusted based on multiple variables.


        Also, try pumping the primer bulb as it's idling rough when cold. Since it idles nicely when warm leads me to believe its not the carbs.


        1982 Whaler Montauk 90HP( sold)[br]1977 25 Mako CC 225HP

        Comment


        • #5
          Okay i would never have thought of that. Thank You.
          quote:


          Originally posted by Headcase


          Also take a look at the impeller and maybe gear oil. If you have something putting additional strain on engine while its trying to idle cold, it could cause it to stumble. When the gear oil or impeller heats up, less resistance so no stumble. You could drop lower unit and see how it starts/idles cold to rule out these two things.


          I agree if it runs ok at idle when its warm, not likely the carbs.


          1982 Whaler Montauk 90HP( sold)[br]1977 25 Mako CC 225HP

          Comment


          • #6
            quote:


            Originally posted by rustyolddad


            Yes the motor purrs after the it warms up...in and out of gear at 8-900 rpms and never misses a beat.

            The choke is built into the key control. You push in when starting to choke. Not sure you can push in when already running, but will try. Primer bulb gets rock hard on prime, but i can certainly try that.

            quote:


            Originally posted by mrdelgado


            Does it smooth out at all if you hit the choke/purge solenoid to give it more fuel? A cold engine needs a Rich fuel condition. The carbs are jetted for operating temp (Leaner condition). That's why fuel injection is nice, AFR is adjusted based on multiple variables.


            Also, try pumping the primer bulb as it's idling rough when cold. Since it idles nicely when warm leads me to believe its not the carbs.



            You can. I used to have to purge some gas in every couple seconds to keep mine running. You can also manually open the purge value on the engine. The red lever on the purge solenoid.
            [br]Michael R. Delgado[br]1972 Mako 22[br]http://classicmako.com/forum/topic.asp?TOPIC_ID=15745[br]1976 Mako 25[br]http://classicmako.com/forum/topic.asp?TOPIC_ID=18013&SearchTerms=mako,25[br]

            Comment


            • #7
              Thanks Mike: I found the purge valve . I will try the extra priming during start. I confirmed the electromagnet is operational, and I ordered a rebuild kit for the purge valve. Bonus because the kit comes with a schrader valve entry port. Found an inline fule valve under the hood, even though i have a large water separating filter in the stern. Will change that also to be safe.
              1982 Whaler Montauk 90HP( sold)[br]1977 25 Mako CC 225HP

              Comment


              • #8
                Thank You Mr. Delgado:

                The choke trick worked great ! I just had to press the key switch a few times and the rough idle is GONE!

                Took the boat on a 50 mile run and all worked very well. Now just have to talk myself into keeping what I think is too big a boat!

                Have to admit I sure do love how this boat rides!
                1982 Whaler Montauk 90HP( sold)[br]1977 25 Mako CC 225HP

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