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electric choke adjustment

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  • electric choke adjustment

    I've got a 2 barrel mercarb on my 4.3 lx. Since I've owned it I've always had trouble starting it cold. Today I'm looking at the carburetor and noticed the electric choke is set to the leanest position. Why would this be? Maybe the previous owner adjusted it incorrectly? Maybe it came from the factory this way? Except for basic maintenance work this motor appears to be completely unmolested and in beautiful condition. No oil leaks of any kind, all paint in great condition and no rust spots anywhere. So, why would this electric choke be adjusted so lean. I've enclosed a pic of the setting on the choke as I found it. I'd say it needs to be adjusted more rich (counter clockwise) . Could this contribute to my hard cold start issue? Am I missing something here?
    1996 Glastron 185GS fish and ski
    4.3LX Gen+ (190 hp 2 barrel carb)
    Alpha 1 Gen 2 S/N 0F 845543

  • #2
    In looking at the picture, it looks as though the choke plate is almost closed which should be sufficient for cold starts (depending what area you live in). Cold start issues are often "operator error" rather than mechanical so lets start with that. 1) Are you pumping the throttle lever a couple times and 2) using the throttle only position to provide a little throttle for startup? If you are, then on a stone cold engine, loosen the two screws on the adjustment plate, rotate the plate so the choke plate begins to open, then go back the other way until it just closes. Done. DO NOT DO THIS ON A WARM ENGINE.

    Comment


    • #3
      Please describe how you start it when cold.

      if you are not pumping the throttle at least twice (primes the motor and sets the choke)

      Silvertip has the right proceedure. With the throttle at about 1/4 way, hit the key. Once the motor fires, back off throttle to 1500 rpm for a minute or so
      1988 Cruisers Rogue 2420 -VP 290 DP now powered by custom 468 - http://forums.iboats.com/forum/owner...988-rogue-2420

      Past Boats
      1970 Wooster Hellion - Merc 9.8
      2002 SeaRay 190BR - 5.0 - A1G2 - "Cheasheads in Paradise"
      1984 Avanti 170DLI -3.0 stringer- "Ship Happens"

      What’s behind you doesn’t matter.Enzo Ferrari

      Comment


      • #4
        The start up procedure you describe is what I've been doing but I continue to have issues. I began to look more closely at the carburetor to begin eliminating possible causes. In the past once the motor did start it ran smoothly. But on the last 2 cold starts it has run very rough.It will smooth out but will die if I don't give it significant throttle. That takes a couple minutes. I also see some smoke from the exhaust that appears mostly white but a bit bluish as well. I will need to run it again to verify the color of the smoke and whether it smells of gas. This motor always seems a bit sluggish on cold start. It just doesn't fire the way I'd expect. I had the battery load tested and it is good. Although that was at the local parts place (Napa) and I'm unsure how well it was tested. I'm tempted to try my truck battery as a comparison. I'm really just trying to determine the cause of the smoke and I didn't want to start it again until I had checked some possible causes first. The smoke goes away after warm up and starting is normal there after. Water temp is consistently around 165 once warmed up The motor oil looks clean and is at the correct level. What else can I check? I will pull the plugs and see what they look like. I will adjust the electric chock as described above and tomorrow will start it again and pay closer attention to the smoke.
        Thanks for the help
        Jcris
        Last edited by Jcris; October 6th, 2017, 11:10 PM.
        1996 Glastron 185GS fish and ski
        4.3LX Gen+ (190 hp 2 barrel carb)
        Alpha 1 Gen 2 S/N 0F 845543

        Comment


        • #5
          blue tint is oil vapor

          it should not run rough at all. giving it throttle and having it die is a symptom of an issue with the accelerator pump circuit. could be debris or crud in the passage.

          do you get two streams of fuel when moving the throttle with the engine off?
          1988 Cruisers Rogue 2420 -VP 290 DP now powered by custom 468 - http://forums.iboats.com/forum/owner...988-rogue-2420

          Past Boats
          1970 Wooster Hellion - Merc 9.8
          2002 SeaRay 190BR - 5.0 - A1G2 - "Cheasheads in Paradise"
          1984 Avanti 170DLI -3.0 stringer- "Ship Happens"

          What’s behind you doesn’t matter.Enzo Ferrari

          Comment


          • #6
            This morning I adjusted the electric choke and found it to be way off. I loosened the 3 screws and rotated it until the choke plate began to open and then rotated back until it just closed. I did this several times to be sure the setting was consistent. This setting was way different than where it was set previously. Then I checked the fuel supply while manually moving the throttle at the carburetor. There was no fuel flow at all. I thought this couldn't possibly be right so I repeated it several times while propping the choke plate open, with eyeglasses in place and a light just above the carburetor throat. No fuel! I found it difficult to actuate the throttle manually so I lubed any points that looked like they may hinder easy movement. Lubricating the linkage didn't help much. I have not started the motor in 3 days which in the past has consistently led to hard starting. As a work around I installed a temporary switch on the fuel pump to "prime" the bowl with fuel. This made a big difference. Now when I pump the throttle manually I get 2 solid streams of fuel. Is it rebuild time for this carburetor? Why would the carburetor bowl drain down like this? This has been a consistent issue since I bought this boat. I don't see how this could relate to the smoking issue but if I can clear this up then I can look more closely into that.
            What do you guy's think?
            Last edited by Jcris; October 7th, 2017, 02:27 PM.
            1996 Glastron 185GS fish and ski
            4.3LX Gen+ (190 hp 2 barrel carb)
            Alpha 1 Gen 2 S/N 0F 845543

            Comment


            • #7
              most likely the carb is leaking into the intake

              pull the carb, do a rebuild. there are two welsh plugs that need to be sealed with epoxy
              1988 Cruisers Rogue 2420 -VP 290 DP now powered by custom 468 - http://forums.iboats.com/forum/owner...988-rogue-2420

              Past Boats
              1970 Wooster Hellion - Merc 9.8
              2002 SeaRay 190BR - 5.0 - A1G2 - "Cheasheads in Paradise"
              1984 Avanti 170DLI -3.0 stringer- "Ship Happens"

              What’s behind you doesn’t matter.Enzo Ferrari

              Comment


              • #8
                I can't quite remember from the armchair and having had a few beers, but I didn't think there was an adjustment on this. It's either working or it isn't.
                Most disconnect it and lock off in the fully choke off position, then simply pump the throttle 10 times or so before starting. Then open throttle half way and crank. When she fires, catch her on the throttle and let her warm up for 5 mins or so.

                Comment


                • #9
                  All carbs with a choke have a way of slightly opening the choke a fraction of an inch to give the engine enough air to keep running. This is called the choke pull off or vaccum break. So if you watch someone else start it, you should see the choke close, or come very close to closing. Then, when it starts the choke plate should be pulled open just a bit. If not the mixture will be too rich and you can get stalling, rough running and black smoke out the exhaust.
                  1988 Four Winns 200 Horizon
                  4.3 OMC Cobra

                  98 Jeep Grand Cherokee 4.0 Selectrac
                  07 Jeep Grand Cherokee Limited 5.7 Quadradrive II

                  "While air doesn't freeze....rust never sleeps"

                  Comment


                  • #10
                    It's possible that your "normal" idle mixture might be a tad lean and/or your accelerator pump(or you) is(are) not pumping as much as fuel as needed before initial cold starting.

                    I don't have as hard a time starting cold and my automatic choke has been completely disconnected for nearly 11 years...........
                    1987 FourWinns 211 Liberator, Originally OMC 460 King Cobra.
                    Re-powered in 2006 with a 1997 Mercruiser 7.4L Bravo III
                    THERE IS NOTHING LIKE A GOOD OIL "THREAD"!!!

                    Comment


                    • #11
                      Agreed, my 30 year old Quadrajet puts a healthy squirt from the accel pump when pumping the throttle. That, or lean or clogged idle circuits can be a culprit here.
                      ​Verify that the choke is working right first though.
                      1988 Four Winns 200 Horizon
                      4.3 OMC Cobra

                      98 Jeep Grand Cherokee 4.0 Selectrac
                      07 Jeep Grand Cherokee Limited 5.7 Quadradrive II

                      "While air doesn't freeze....rust never sleeps"

                      Comment


                      • #12
                        Thanks guy's,
                        I'll have to verify proper operation of the choke tomorrow. I have adjusted it and with the ignition on it opens fully in a minute or two. At least I know the coil is working. That whole electric choke set-up seems a bit crappy. The setting is straight forward but there seems to be quite a range in which it will work. I'm still wondering if the smoke I saw was in any way related to a poorly tuned carburetor. Guess I'll find out more tomorrow.
                        1996 Glastron 185GS fish and ski
                        4.3LX Gen+ (190 hp 2 barrel carb)
                        Alpha 1 Gen 2 S/N 0F 845543

                        Comment


                        • #13
                          This is one thing I don't like about electric chokes. They operate on a timer, and open before the engine warms up. While that's good for fuel economy, its not always good for drivability. The old style chokes used a choke thermostatic spring that was heated by the exhaust cross over in the intake manifold. So it opened in response to the actual temperature of the engine, ideally it would be fully open when the engine reached normal operating temps (160 for most newer engines).
                          ​I have seen a conversion for old style QJets to convert them to electric chokes (because the newer style GM vortec engines do not have a heated exhaust cross over in the intake manifold) that does use a temp sensor, to make it work more in sync with the actual engine temp.

                          ​Anyone who has a late model merc shop manual care to look up how this thing is supposed to work?


                          try this first:

                          http://www.boatfix.com/merc/Bullet/97/97_08.pdf

                          http://www.discount-marine.com/club/files/carb.pdf
                          Last edited by Lou C; October 8th, 2017, 08:03 PM.
                          1988 Four Winns 200 Horizon
                          4.3 OMC Cobra

                          98 Jeep Grand Cherokee 4.0 Selectrac
                          07 Jeep Grand Cherokee Limited 5.7 Quadradrive II

                          "While air doesn't freeze....rust never sleeps"

                          Comment


                          • #14
                            Sign up today
                            Thanks Lou,
                            I will revisit the details of those PDF's again tomorrow. I'm also contemplating rebuilding this carburetor. I have the kit on hand but am hesitant to do the work before I understand it more. After reading several forums on the Mercarb 2 barrel it seems they have a history of draining the bowl when not used regularly. Which some suggest can be fixed by using epoxy to re-seal the welsh plugs. Honestly, I'm unfamiliar with welsh plugs. Similar to freeze plugs I guess. If they exist and I actually do rebuild the carb I'll find and re-seal them, just to be sure.
                            Thanks again
                            Last edited by Jcris; October 9th, 2017, 12:34 AM.
                            1996 Glastron 185GS fish and ski
                            4.3LX Gen+ (190 hp 2 barrel carb)
                            Alpha 1 Gen 2 S/N 0F 845543

                            Comment

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