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2012 175 BR question-gctid813417

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    2012 175 BR question-gctid813417

    Hi all,

    I have a 2012 175 BR that I bought last year. Great little boat that's a ton of fun. I'm having an issue with the engine continuing to roll over for up to 20-30 seconds at time when I kill the engine. It's the worse when I've gone from fast to slow and turned off the engine without letter the boat idol for a while (which I don't do anymore). Anyway just wanted to see if anyone experienced this with their boats and if you have any remedies. Thanks in advance for your help/advice.

    Attached files

    This is a common problem with the 3 liter engine. You have to let it idle before shutting it down. You can use higher octane gas, but the engine only need 87 octane.
    1998 Capri 1950CL
    3 Liter MerCruiser
    Furuno 1622 Radar, Garmin echoMAP44dv, Garmin 300 AIS receiver, Uniden Cl 2 VHF with Hailer,
    2 batteries with Combiner, Joystick Wakeboard Tower


      Had a similar issue with my 2010. Is it the TKS system (carb)? Smelled like gas occasionally? Always running blowers? One mod I'd think you'd deeply enjoy is fuel injection. Expensive, but Bayliner would sell hundreds more of these 175s with just two mods: EFI and great engine sound insulation. I know, hear they're the best selling boat in the world already. But if EFI is 3k, do it.
      It is when you give of yourself that you truly give - Kahlil Gilbran
      2015 Bayliner 642 in Red, 4.3L MPI, Alpha 1 Gen II
      Eagle Runner


        It's called "run-on" or "dieseling" and it is typical with the 3 liter motors, and noted above. As simplistic explanation is that it is usually caused by unburned fuel causing carbon deposits at the top of the cylinders, in combination with some fuel remnants remaining in the cylinders after shut off. The carbon deposits can stay hot, above the flash point of the fuel mixture, and the engine effectively runs like a diesel based on the "glow" of the hot carbon.

        It is potentially harmful since you could break a piston or bend a con rod or have a similar catastrophic failure. If the engine starts to do it, you can simply re-start the engine by turning the key back on (WITHOUT engaging the starter!!!)

        Possible solutions:

        1) Higher octane fuel can reduce it, either by reducing carbon buildup or by being harder to ignite (I am not sure which is the reason but it worked for my 2007 3.0).

        2) An anti-carbon additive such as Yamaha ring-free or Carbonex can reduce carbon buildup.

        3) Shutting it down in gear can prevent run-on.

        4) As noted above, letting the engine idle for a minute or two prior to shut down will cool the carbon a bit and/or reduce the fuel remnants in the intake side of the engine, and thus reduce run-on.