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1990 7.4L w/B2 idle problems

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    #16
    What's the best way to check for vacuum leaks. There are no vacuum hoses.

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      #17
      Use a spray bottle with water in it and mist the gasket interfaces one area at a time. If there is a leak it will suck in the water and the idle will temporary increase.
      1997 Maxum 2400 SCR 5.7LX Bravo II

      Mike

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        #18
        Originally posted by trimjb View Post
        This is the fuel pump. Pretty crusty, Out of site out of mind.
        In the FWIW department, w
        hen my fuel pump diaphrams (yes both apparently) began leaking, I ended up with a lot of fuel in the crankcase, but did not lose idle or carb issues. While fuel "should" have been evident in the "sight glass", it wasn't. The reason ended up being that both the "sight glass" (really just a yellow piece of tubing) fuel pump and carb fittings were totally blocked with green corrosion. The boat did do a lot of sitting in the cradle idle with the PO and prior to our ownership, so no telling why that line had gotten water/vapor/junk in it to corrode closed, but when I pulled the fitting from the carb there was no way to get air let alone gas through it. Thus I guess the fuel ultimately had to go somewhere.

        All that said - I never lost smooth idle or running such as Trimjb is experiencing. I was also wondering if it could be possible the neutral safety switch is a bit misadjusted causing the stall? I know if I hesitate to long going from gear to neutral that mine will stall. Just another thought to add to the confusion.

        1998 BL Ciera 2655 Sunbridge LX (Special Edition)
        "Sea Flights"
        5.7L 2bbl w/Thunderbolt Ignition
        Alpha I Gen II Sterndrive with raw water cooling
        MFG Extra's - A/C, Fresh Water Engine Flush port, HWH and Windlass
        Docks @ Punta Gorda, Florida

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          #19
          Conch, yes shift interrupt switch on your dog clutched A1G2.
          no shift interrupt switch on Bravos since it's a cone clutch drive.
          Joon, Kathy, Jaden & Tristan
          93 3058
          92 2855
          91 Fourwinns 205
          Longbranch WA
          Life is Good

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            #20
            Originally posted by Ruffryder View Post
            Conch, yes shift interrupt switch on your dog clutched A1G2.
            no shift interrupt switch on Bravos since it's a cone clutch drive.
            Ahhhhh....thanks. I'm not familiar with the Bravos and didn't know that. Now I've learned something new! Thanks for the info.
            1998 BL Ciera 2655 Sunbridge LX (Special Edition)
            "Sea Flights"
            5.7L 2bbl w/Thunderbolt Ignition
            Alpha I Gen II Sterndrive with raw water cooling
            MFG Extra's - A/C, Fresh Water Engine Flush port, HWH and Windlass
            Docks @ Punta Gorda, Florida

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              #21
              +1 to Joons comments
              BTW there is a neutral safety switch but it’ll just keep her from cranking.
              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

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                #22
                Well, I solved the mystery.
                Spark Plugs. I went to change out plugs this morning and found all 8 had cracks in the porcelain. All 8 had 3 cracks almost in even 3rds lengthwise. 6 of the 8 the porcelain had complete broken off at the hex when I was removing them. No, I didn’t put pressure on the porcelain. On one plug the porcelain came off in the spark plug boot. I test ran and back to normal idle. Runs smooth, no missing.
                Everything else I did needed to be done regardless.
                Thanks for all the suggestions.

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                  #23
                  Glad you were able to resolve the issue for minimal cost. Surprised it wasn’t missing across the entire power band.
                  1997 Maxum 2400 SCR 5.7LX Bravo II

                  Mike

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                    #24
                    Well she won't run/idle with 8 of those installed. How many hours on those plugs, what does the electrode end of the plugs look like?
                    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

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