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3.0L runs bad out of storage. Carb AP pump or spark plug??-gctid397600

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    3.0L runs bad out of storage. Carb AP pump or spark plug??-gctid397600

    Hi all!

    Original owner of a 09' 175BR w/ carb'd 3.0L merc. Winterized myself (stabil'd the 1/3 tank of gas, oil change, gear lube change, drain water, fogged cylinder, new plugs before firing up for the season). And I cleaned the recently installed fuel water separator as well. I did not have any issues before I parked it for the winter.

    About a month ago we had a brief heat spell, so I got the damn boat out and ran it on the muffs. No problems at idle or small throttle openings with no load on the motor, so off to the river we go. I launch, start her up and let her warm up as I park the truck. Everything is going great until we get out to open river and I try to get her on a plane. At about 1/4 throttle she stumbles, but will recover if I give it more gas and then runs perfect between 1/3 and WOT. I thought the carb screw might need adjusting, so I tried a 1/4 turn in (no real change) and then reset and tried a 1/4 turn out (no real change). We then beached the boat, swam and returned home with the problem unsolved.

    Summer finally hit here in Portland, so I got the DB out yesterday to try to tune out this problem. Launched the boat, fired it up and let it idle while I parked the truck. It idles good until warm, so off we go. I get it out to open river and it has the same bog at 1/4 throttle (around 2k rpms), but will run perfect after the bog. I play with the screw from almost seated to a few turns out and now I cant get the damn boat to start without a serious amount of throttle and once started it will not run without at least 1/4 throttle to keep it going. It almost feels like its running on 3 cylinders.

    I need to reset the fuel screw (stock is 1 1/4 turns out, correct?), but there's still an underlying issue. Boat ran perfect last year, I stored it over the winter and now runs like crap. The only things I changed are the plugs... did I possibly foul one upon first start of the year (with all the fogging oil in the cyls) and its progressively gotten worse? Or is this a carb issue?

    It ran bad early in the day and then progressively got worse until it wouldn't start or run without some throttle applied. I dont want to throw money at it until I know where to throw it.

    Any advice would is greatly appreciated!

    #2
    sounds like the accelerator pump in the carb is the issue.

    wish you didn't start adjusting the idle mixture screw though. need to set that back properly.

    that screw is for setting the mixture at idle only.

    I also don't see any mention of cleaning the flame arrester atop the carb. that never hurts.

    I would start it cold and watch the choke plate too - make sure it's opening properly when hot.

    Comment


      #3
      If this were mine, I would be doing the easiest first: Replace the fuel/water filter with a new 10 micron spin-on elememt.

      Your post suggests that you tried to "clean" your old filter, and they are not the kind that you can 'clean' and reuse. Your tank may have some gunk at the bottom, and that may be take several filters to eliminate.

      Happy boating!
      Boating Supplies

      Comment


        #4
        http://www.marineengine.com/boat-for...631#post338631
        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


          #5
          Thanks for the links.

          I installed some new AC's (Napa calls them AC rapidfire #8), gapped them to .045, set the idle screw to 1.5 turns out and she fired up. It idled okay until it started to warm up a bit and then began to stumble and eventually die. When cold it ran pretty decent though, so the choke was compensating to allow it to run.

          I think its safe to say I've got a fuel issue. The boat has 41hrs on it and I installed a Racor fuel water separator not too long ago (7hrs run time maybe!?) and I drained it after the season last year. I did not replace, but I did loosen the drain cap and let the contents drain in case there was water in there. I also have never cleaned the filters in the pump nor the carb inlet. I'll try a old fashioned fuel system cleaning and see how she goes. Thx!

          Forgot to ask...

          Since I have installed an inline filter/water separator is it safe to remove the OEM filters?

          Comment


            #6
            DamnBoat wrote:
            Thanks for the links.

            I installed some new AC's (Napa calls them AC rapidfire #8), gapped them to .045, set the idle screw to 1.5 turns out and she fired up. It idled okay until it started to warm up a bit and then began to stumble and eventually die. When cold it ran pretty decent though, so the choke was compensating to allow it to run.

            I think its safe to say I've got a fuel issue. The boat has 41hrs on it and I installed a Racor fuel water separator not too long ago (7hrs run time maybe!?) and I drained it after the season last year. I did not replace, but I did loosen the drain cap and let the contents drain in case there was water in there. I also have never cleaned the filters in the pump nor the carb inlet. I'll try a old fashioned fuel system cleaning and see how she goes. Thx!

            Forgot to ask...

            Since I have installed an inline filter/water separator is it safe to remove the OEM filters?
            It sounds like you were doing fine after installing the Racor for the last 30+ hours. I am hoping that your Racor is not the one with the clear bowl w/the drain cock...that would be a Coast Guard violation if you ever get boarded.

            It also sounds like you have only drained any water from the bottom of your Racor. The rule of thumb is to replace the filter itself every season, and your actual paper filter may be partially clogged (doing it's thing!).

            As for the OEM filters: Your Racor is your first line of defense, and there is very little that will get past that and into your OEM filters. If this were mine, I would not be concerned about the OEM filters, and would not disturb them.

            Happy boating!
            Boating Supplies

            Comment


              #7
              The Racor is the USCG approved w/ the metal bowl. Good looking out though.

              I've replaced the Racor filter, removed the fuel pump filter entirely, cleaned the filter by the carb (which barely had any debris) and replaced the spark plugs. The only fuel related thing I cannot get to is the pickup screen inside the tank as I cant get the elbow adapter to budge and dont want to break anything.

              Anyway, now it wont idle at all and it requires quite a bit of throttle to start it or to keep it running. If I allow it under 1/4 throttle then it just dies instantly. When the motor was cold it ran way better and now that's it hot (the motor and air temp) it has gone downhill. Choke issue maybe? Dirty pilot jet?

              First heatwave of the year and I'm out sweating under a boat engine cover. This stinks!

              Comment


                #8
                Try a few tanks of non-ethanol gas and seafoam. Sounds like your gas went to crap over the winter. I have alot of problems with my motorcycles if I use ethanol gas and don't ride for a month.

                Comment


                  #9
                  Not too surprisingly it was the carb. I tore it down, cleaned, rebuilt and ran her all day yesterday.

                  I spent $60 for a carb rebuild kit, but only ended up using 2 gaskets. The QS supplied jets were cheap unstamped knock off's and the fuel screw they supplied was 1/16" shorter than the OEM one. My motor only has 40hrs and all the OEM jets, plunger, etc. looked perfect.

                  I cant quite seem to find the balance between easy starting and no dieseling though. If I go in on the fuel screw I can get it to fire up easy, but it seems to idle a little rough and will diesel after being ran hard. I had the perfect settings before the carb rebuild, but I couldn't seem to find it yesterday. The boat ran great besides this. Thanks!

                  Comment


                    #10
                    Mine would diesel too if I cut the motor shortly after running hard.

                    Let it idle for a while after running hard before killing it, that worked for me.

                    And try to avoid gas with ethanol.

                    One of my motorcycles has to have the carb taken apart and cleaned every time if I dont ride it for a month or more and I put gas with ethanol in it. It is very finnicky like those 3.0 carbs.

                    Comment

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