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    Idle hesitation, spark plug ?, etc...

    Only a few more weeks here until I can actually start the boat & have her ready for the summer! In the meantime as it warms up, I am trying to get ahead of some late season issues I was having.

    Last season, idle would bounce slightly between 650 & 750 in the water (doing the same on muffs, just higher RPMs). never had a perfect purrr. Adjusting the idle up or down slightly didnt make a difference in the hesitation. I would also experience the boat stalling when slowing down, usually stalling right before the boat would hit an idle or very low wake speed. Starts right back up and would let me run at low speeds, just kills when coming down from a cruise.

    It wasnt overbearing for the use last year, but want it to run as it should this year. Was the first year I owned the boat (but had been with trusted family friends as only other owner). Previous year had a full tune with cap, distr, plugs, & wires.

    I just cleaned the screen which connects from fuel line to carb. Fairly gunked up(see below). Just ordered a new fuel filter for the pump, assuming it is a shit show. What is the likelihood my jets got gummed up as well, knowing the screen was nasty, & thoughts on needing to go through a carb cleaning?

    My second issue here is the spark plugs. I ordered a set of the manufactured recommendation acdelco. I then just went and pulled a plug to inspect, which it has Champion rc12yc plugs in it currently. Arent these shorter plugs? Should I trust what was in the motor, over the flame arrestor cover? Or could the current plugs explain some of the idle issues (although it seems to be fuel related for sure after todays inspection)?

    Appreciate your time in advance and expert advice. Trying to turn my mechanical knowledge into not being boat dumb.


    #2
    That screen" is actually one of the filters. They are not built, or meant, to be cleaned, just replaced. Something gummed up that badly would indicate a contaminated fuel source. I'd suspect that your tank should drained and cleaned (professionally). As to your carburetor question, yes, it'll likely need to be cleaned and rebuilt. Once the above is done, your engine idle problem will likely be resolved. As for the spark plugs I'd go with the manufactures recommendation (not necessarily the one on the flame arrestor, it mightn't be the original).The number should be in the operating manual, or available from a Dealer
    Bob Hawes.
    Kelowna, B.C.
    1998 Trophy 2052 WA
    4.3 Vortec, A1 G2

    Comment


      #3
      What year engine ?

      Make sure your choke is opening all the way.

      Have a fuel / water seporator ?

      Dump the contents in a clear, clean glass jar let sit, see water on the bottom ?

      compession is what on all the cylinders ?
      Be good, be happy, for tomorrow is promised to no man !

      1994 2452, 5.0l, Alpha gen. 2 drive. Sold ! Sold ! Sold !

      '86 / 19' Citation cuddy, Merc. 3.0L / 140 hp 86' , stringer drive. Sold ! Sold ! Sold !

      Manalapan N.J

      Comment


        #4
        Four spark plugs is an inexpensive way to check if that caused your idle issues. Based on the screen pic I'd say that it's also likely debris in the fuel has found its way into the idle circuit of the carb.
        Dave
        Edmonds, WA
        "THE FIX"
        '93 2556 5.7 Bravo II 2.0:1 18 1/4x19 P
        (.030 over-Vortec top end-part closed cooled)
        The rebuild of my 2556 https://www.baylinerownersclub.org/f...76?view=thread
        Misc. projects thread
        https://www.baylinerownersclub.org/f...56-gctid789773

        Comment


          #5
          Short of the fuel being old, separated, or having moisture in it, here are a few things that can cause an idle porblem... if there os any fuel gum or varnish problems seafoam will dissolve it within a few hours, but if a particle got thru the filter, seafoam cant dissolve that, so the carb may need to be removed and cleaned....

          a plug or plug wire can cause a weak or.non existant spark in the cylinder, and so can worn distributor shaft bushings, or ignition points that have developed a "tit" on one of the contacts.... also check for any play where the throttle shaft passes thru the carb, as this can allow the shaft to move just slightly enough to cause a change in the airflow/fuel flow at an idle.... and so can a vacuum leak elswhere in the system..


          NU LIBERTE'
          Salem, OR

          1989 Bayliner 2556 Convertible
          5.7 OMC Cobra - 15.5x11 prop
          N2K equipped throughout..
          2014 Ram 3500 crew cab, 6.7 Cummins
          2007 M-3705 SLC weekend warrior, 5th wheel
          '04 Polaris Sportsman 700 -- '05 Polaris Sportsman 500 HO
          Heavy Equipment Repair and Specialty Welding

          Comment


            #6
            First, thanks to all here. bunch of good knowledge and quick replies. We must all just be itching to actually boat ehh?

            Originally posted by Chief_Alen View Post

            What year engine ? 2003 175 is the boat, original motor with the boat, but not 100% that its an 03 motor as well (if its a few years newer or older). going to look tonight for serial on the motor in case the flame arrestor cover is saying something different.

            Make sure your choke is opening all the way. Checked this last year, choke and the throttle cable are functioning properly.

            Have a fuel / water seporator? No. I was shocked to find these motors are only supported by the tiny filter on the fuel pump & no true water seperator. I plan to install a kit, just need to locate one that is the right size.

            Dump the contents in a clear, clean glass jar let sit, see water on the bottom ? I plan on buying a cheap fuel pump from the auto store and doing this. I am on the side of field with full tank & stabilizer (instead of the empty tankers) during off-season. Might be fun trying to find somewhere to pull out 10+ gallons of gas. Initial goal is to just pull the bottom corner of the tank to see the outcome, then pull the rest of the gas if needed.

            compession is what on all the cylinders ? TBD. Not sure if weather is going to play nice, so waiting another week or two before I fire the motor up, change plugs, etc... Working to make sure my fuel system is all set before I even fire it at this point.

            @Centerline2 - plugs, wires, cap & all were just replaced two years ago. Not saying they are fine, which I will inspect the rotor & all when I do the plugs. I dont foresee this being an issue. I am more concerned that the motor had the shorter Champion plugs in the motor, while I see it calls for the longer reach ACDelco's.

            Comment


              #7
              The wrong length of plug can cause more than just idle.issues... so be absolutely certain your engine takes the longer plugs...
              Against my better judgement, i followed some faulty information given to me by a guy at our local speed shop, and it cost me 2 cylinders... all due to the wrong length of spark plug,.

              what motor do you.have?


              NU LIBERTE'
              Salem, OR

              1989 Bayliner 2556 Convertible
              5.7 OMC Cobra - 15.5x11 prop
              N2K equipped throughout..
              2014 Ram 3500 crew cab, 6.7 Cummins
              2007 M-3705 SLC weekend warrior, 5th wheel
              '04 Polaris Sportsman 700 -- '05 Polaris Sportsman 500 HO
              Heavy Equipment Repair and Specialty Welding

              Comment


                #8
                Originally posted by Centerline2 View Post
                The wrong length of plug can cause more than just idle.issues... so be absolutely certain your engine takes the longer plugs...
                Against my better judgement, i followed some faulty information given to me by a guy at our local speed shop, and it cost me 2 cylinders... all due to the wrong length of spark plug,.

                what motor do you.have?
                Merc 3.0, 4 banger. I see everyone says the gap should be 35, but that info also differs from what my flame arrestor. Definitely my largest concern is plug length and not destroying my motor putting a longer plug in there than what it has been running off of. Knowing a tune upwas done 2 years ago with the Champion plugs, I am thinking that they may have just put the wrong ones in.

                Comment


                  #9
                  Older manual says .35, arrestor will say .45.
                  Mercruiser changed it in service bulletin in 2006.
                  Use A.C. MR43LTS set to .45.
                  Joon, Kathy, Jaden & Tristan
                  Uniflite 42 AC, DD 671N
                  93 3058 sold
                  92 2855 (day boat)
                  91 Fourwinns 205 (lake boat)
                  Longbranch WA
                  Life is Good

                  Comment


                    #10
                    Not sure where you live or what conditions the boat was operated in, but replacing plug wires yearly on a 4banger is cheap insurance. You might have an arcing wire somewhere.
                    Guessing a carb rebuild is in your near future, as well as the plugs.
                    97 2859

                    Comment


                      #11
                      Low compression on even one cylinder you will never get the engine to idle right .

                      Be good, be happy, for tomorrow is promised to no man !

                      1994 2452, 5.0l, Alpha gen. 2 drive. Sold ! Sold ! Sold !

                      '86 / 19' Citation cuddy, Merc. 3.0L / 140 hp 86' , stringer drive. Sold ! Sold ! Sold !

                      Manalapan N.J

                      Comment


                        #12
                        Does it say Tks on the arrester ?

                        https://www.marineengine.com/parts/m...uretor-kit-tks
                        Be good, be happy, for tomorrow is promised to no man !

                        1994 2452, 5.0l, Alpha gen. 2 drive. Sold ! Sold ! Sold !

                        '86 / 19' Citation cuddy, Merc. 3.0L / 140 hp 86' , stringer drive. Sold ! Sold ! Sold !

                        Manalapan N.J

                        Comment


                          #13
                          Originally posted by Chief_Alen View Post
                          Yea its a TKS system. I was cleaning out the well under the motor and found an old spark plug, which is the AC Delco. So I am sure that whomever did the tune up previously just threw some cheap Champion plugs in that they had in the shop.

                          I have an electric pump I was able to borrow, so will be draining out my fuel tank and replacing the fuel lines to ensure that is all clean. The fuel filter was pretty beat up when I replaced it earlier this week (yet alone how big a pain in the arse it is to replace).

                          Pretty sure I can contribute most my issues to the wrong plugs and dirty fuel system. If I still have issues after a clean fuel system, the right plugs, & solid compression results, then I will know that the carb rebuild wont be a waste.

                          Comment


                            #14
                            No Personall experience with the TKS but Chief points out a great possible cause of your idle issue with it being a TKS. Those little units go bad quite often.
                            Dave
                            Edmonds, WA
                            "THE FIX"
                            '93 2556 5.7 Bravo II 2.0:1 18 1/4x19 P
                            (.030 over-Vortec top end-part closed cooled)
                            The rebuild of my 2556 https://www.baylinerownersclub.org/f...76?view=thread
                            Misc. projects thread
                            https://www.baylinerownersclub.org/f...56-gctid789773

                            Comment


                              #15
                              The TKS does not have a choke but instead an enriching circuit that adds more fuel when cold. Issues range from gummed passage, faulty temp sensor, faulty plunger.
                              1997 Maxum 2400 SCR 5.7LX Bravo II

                              Mike

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