Please note this thread has been inactive for 90 days. For the best results, please start a new thread.
Results 1 to 6 of 6
  1. #1
    Seaman Apprentice
    Join Date
    Aug 2012
    Posts
    38

    Default Mercruiser 300 dies on the water

    Older boat and motor, but new to us, so we don't know the history. Bought it from a dealer, and here in Illinois it would be a fresh water boat.

    Engine starts immediately and runs fine. We've had it on the water three times and each time it quit after an hour. We don't see any common cause or event in the three times. Rough water or smooth water, WOT and slower. Temp guage shows normal range. Each time we got towed as it would NOT restart, but the next day on muffs, it fires right up.

    Hmm. Where do we look. I'm guessing fuel line, but would appeciate all replies as we are new to boating so have no experience. Thanks.

  2. #2
    Vice Admiral tpenfield's Avatar
    Join Date
    Jul 2011
    Location
    Cape Cod, MA
    Posts
    5,919

    Default Re: Mercruiser 300 dies on the water

    I would start by verifying that the vent for the fuel tank is clear and allowing air in/out.
    Best regards,
    Formula 330 Sun Sport
    Twin Mercruiser 7.4 LX MPI (0F802036, 0F802039), Bravo 3's (0F806198, 0F806199)
    1969 Mercury 7.5 HP Outboard (26346XX)
    .
    My Formula 330SS Web Site: -> Link
    My Formula 242SS Web Site: -> Link
    My Catalina 22 Web Site: -> Link

    Member of the Month - February 2013 http://www.iboats.com/blog/tpenfield...-of-the-month/

  3. #3
    Honorary Moderator Emeritus Don S's Avatar
    Join Date
    Aug 2004
    Location
    Western WA.
    Posts
    62,323

    Default Re: Mercruiser 300 dies on the water

    When it dies, do you still have spark? Do you get fuel out of the accelerator pump holes in the carb if you pump the throttle?
    Don S.


    Please, no PM's (Private Messages) regarding boat/engine problems.
    That is what the forums are for.
    Only forum/moderator issues will be answered in PM's.

  4. #4
    Seaman Apprentice
    Join Date
    Aug 2012
    Posts
    38

    Default Re: Mercruiser 300 dies on the water

    Thank you both for the reply. We'll check the gas line and tank vent here at home next we pull the boat out of the shed, but Don's questions won't get answered until we're in the water if the problem comes back.

    This was just what I was hoping for: a few suggestions to get us started. Thank you!

  5. #5
    Senior Chief Petty Officer
    Join Date
    Apr 2009
    Location
    Richmond/Montross, Va
    Posts
    794

    Default Re: Mercruiser 300 dies on the water

    You don't need the boat in the water to try don's suggestions...
    '86 Glastron Conroy X-19
    Merc 170

  6. #6
    Seaman Apprentice
    Join Date
    Aug 2012
    Posts
    38

    Default Re: Mercruiser 300 dies on the water

    Turned out to be electrical. Kill switch wire was shorting. End of topic.

Similar Threads

  1. 150hp Mercury run great out of water dies when put in gear when in water
    By stophie11 in forum Mercury & Mariner Outboards
    Replies: 8
    Last Post: August 31st, 2011, 08:49 AM
  2. HELP!mercury 1992 black max run fine out water but dies in water
    By jeremy.lail in forum Mercury & Mariner Outboards
    Replies: 1
    Last Post: August 3rd, 2009, 07:59 AM
  3. Mercruiser 5L dies at WOT
    By doc_cody_blue in forum Mercruiser I/O & Inboard Engines & Outdrives
    Replies: 2
    Last Post: June 18th, 2009, 08:42 AM
  4. PLEASE HELP!! Mercruiser DIES!!
    By goneboating06 in forum Mercruiser I/O & Inboard Engines & Outdrives
    Replies: 58
    Last Post: July 2nd, 2008, 01:10 AM
  5. Mercruiser 5.7 dies when hot
    By Bigmo83 in forum Mercury & Mariner Outboards
    Replies: 2
    Last Post: August 5th, 2002, 12:44 PM
  1. iboats Forum Directory - Over 100,000 forum posts organized by topic