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  1. #1
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    2005 Mercury Optimax issue

    Let me start this off by saying I am not mechanically inclined. I have 2005 Optimax that sat for about 5 years without running. I had the old gas taken out, filter changed and new gas put in. 2 of the plugs were pulled and looked fine. I have had the boat out 3 times since. The first time I run it each time on the water it's a dog to get up on plane. When it finally does get up it runs around 4000 rmps and about 40-45 mph. It will then pick up rpms and speed to around 5000 and low 50's but it will drop back off and pick back up on it's own. I stop and fish and the next time I go to get up on plane and every time after that it gets on plane with no issue but the rmp & speed drop and increase issue is still there. I know I am going to have to take this back to the mechanic but does anyone have any experience with this issue as to what it could be? Water pressure is running around 15 psi. I do have a hydraulic jackplate as well. I've tried a few different heights but I don't think it's a motor height issue. Any suggestions? Thanks in advance.

  2. Member 06 SB's Avatar
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    Feb 2012
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    #2

    USN Retired
    2020 Basscat Caracal
    2020 Mercury 225 ProXS 4s



  3. Member
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    Sep 2018
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    #3
    Sorry forgot to mention I had the fuel line and bulb replaced about 6 years ago to the ethanol proof ones. Not sure if they were replaced right from the tank or not.

  4. Member
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    #4
    Quote Originally Posted by Scooter13 View Post
    Sorry forgot to mention I had the fuel line and bulb replaced about 6 years ago to the ethanol proof ones. Not sure if they were replaced right from the tank or not.
    You also forgot to mention a serial number which is required in this forum.

  5. Member
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    #5
    Sorry I could not get a serial # off my motor at the time. Out of curiosity, why is that required?

  6. Member
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    May 2011
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    Spangle, WA
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    #6
    Quote Originally Posted by Scooter13 View Post
    Sorry I could not get a serial # off my motor at the time. Out of curiosity, why is that required?
    To properly ID your engine since Mercury does not go by years - Please Review the Forum Announcements BEFORE Posting and follow. Thanks!

    Just me, but I would not have run that engine without first having the entire fuel system serviced and verified, 5 yrs is a long time.
    _______

    Phil
    '09 Hewescraft ProV
    '09 150 Optimax


  7. Member 06 SB's Avatar
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    Feb 2012
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    West Point Lake, GA
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    #7
    What Phil said. As an example, there are cases where a 20XX 115 could be a 4 stroke, 2 stroke inline 4cyl or a 2 stroke inline 3cyl. Surprisingly, sometimes owners do not know which one they have!

    Oh, and WELCOME TO BBC!!!

    USN Retired
    2020 Basscat Caracal
    2020 Mercury 225 ProXS 4s



  8. Mercury 3L/4 Stroke/Verado Moderator EuropeanAM's Avatar
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    Apr 2008
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    Greenville, SC (US)
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    #8
    Quote Originally Posted by Scooter13 View Post
    Let me start this off by saying I am not mechanically inclined. I have 2005 Optimax that sat for about 5 years without running. I had the old gas taken out, filter changed and new gas put in. 2 of the plugs were pulled and looked fine. I have had the boat out 3 times since. The first time I run it each time on the water it's a dog to get up on plane. When it finally does get up it runs around 4000 rmps and about 40-45 mph. It will then pick up rpms and speed to around 5000 and low 50's but it will drop back off and pick back up on it's own. I stop and fish and the next time I go to get up on plane and every time after that it gets on plane with no issue but the rmp & speed drop and increase issue is still there. I know I am going to have to take this back to the mechanic but does anyone have any experience with this issue as to what it could be? Water pressure is running around 15 psi. I do have a hydraulic jackplate as well. I've tried a few different heights but I don't think it's a motor height issue. Any suggestions? Thanks in advance.
    As stated above- Welcome to BBC!

    Please take a couple moments to review the Announcements at the top of the Forum, and provide the Required Information with your post. Be glad to try to assist you at that point.

    Thanks!


    Dual Mercury Master Technician- for Mercury Outboards, Mercruiser and Mercury Racing at European Marine in Greenville, SC.
    Still consider myself a "Marine Apprentice" after 47 years (learn something new every day).
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