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  1. #1
    Member
    Join Date
    Oct 2018
    Location
    Roselle, IL
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    106

    Opti idling rough and stalling on start up.

    2015 Optimax ProXS 250
    S/N: 2b111040

    Motor ran fine all morning. We stopped at a bar on the water for lunch and when we came back it started acting up. Boat stayed in the water during lunch.

    On key turn, the motor turns over and starts.
    It immediately starts sputtering and idling rough and then stalls after about 5 seconds.
    It would keep doing this unless I gave it some gas right away to get the RPMs up. It would stay running as long as I stayed on the gas. As soon as I throttle back to idle, it stalls.
    No alarms.

    I was able to actually throw it in gear real quick and get the RPMs up before it stalled to get me to the ramp, and it ran fine all the way back to the ramp. As soon as I came off pad and the RPMs came down, it would stall.

    It feels like a fuel issue, but I could be totally wrong. I didn't have the chance to pull the cowling off yet, but I did check the bulb, and it was hard.

    SIDE NOTE: When getting the RPMs up in neutral, I did throw a 6 beep alarm at me once. Not sure if that's related. I just got this motor in a re-power this past winter and it was throwing cold temperature alarms at first because of debris in the thermostat but I had them cleaned and it hasn't been an issue since. The alarm only happened when giving it gas in neutral for more than a few seconds.

    I'm going to try and get it to my mechanic ASAP, but was wondering what you guys think it might be and if you have anything I should be looking for in the morning when I get a chance to look at it?

    Thanks guys,
    Nate
    2012 Nitro Z8
    225 Mercury Pro XS

  2. Member
    Join Date
    Jun 2013
    Location
    LONGVIEW TEXAS
    Posts
    14,891
    #2
    likely is a fuel psi problem , did you notice it smoking when it started , possible diaphragm in rail failure , 6 beep is overspeed in neutral
    .................................................. ...the scariest thing in life is the unknown ...................................

  3. Member
    Join Date
    Oct 2018
    Location
    Roselle, IL
    Posts
    106
    #3
    Quote Originally Posted by JOE54 View Post
    likely is a fuel psi problem , did you notice it smoking when it started , possible diaphragm in rail failure , 6 beep is overspeed in neutral
    A tiny bit of smoke when giving it some gas in neutral maybe. But nothing that seemed unusual
    2012 Nitro Z8
    225 Mercury Pro XS

  4. Member
    Join Date
    Jul 2004
    Location
    Penn PA
    Posts
    15,507
    #4
    Please stop giving it throttle in neutral, all that does is trigger more faults.



  5. Member
    Join Date
    Oct 2018
    Location
    Roselle, IL
    Posts
    106
    #5
    Good to know. Just did it during on the water testing. Any advice on what might be causing the sputtering and stalling?
    2012 Nitro Z8
    225 Mercury Pro XS

  6. Member
    Join Date
    Jul 2004
    Location
    Penn PA
    Posts
    15,507
    #6
    Need fuel and ait pressures recorded as the problem is occurring.



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