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1999 Mercuriser 454 air in fuel system

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  • 1999 Mercuriser 454 air in fuel system
    I have a 1999 Mercrusier 454 and I am experiencing a lot of air in my fuel system but is allowing the boat to run for a short period of time. I have replaced fuel pick up as well as fuel filter. The tank is full of new fuel. I checked to verify the boat was not vapor locking it is not leaking fuel anywhere.

    I did fuel pressure test running at 55 lbs and I keep getting air out of schrader valve. The engine is efi. Boat will run on idle and acceleration for 3 mintues and then die and will not refire until I purge air out of shrader valve. Did remove fuel cap and found that boat is not vapor locking.

    Any ideas?

  • #2
    Re: 1999 Mercuriser 454 air in fuel system

    What is the seria; number of your engine?
    94 Formula 27PC Custom 509MPI MEFI3 , B3 XR
    95 Rinker 232 w/ 7.4L Carb 0F425011 B1 0F486471
    07 SeaDoo GTX
    Raw Water Pump Maintenance


    • #3
      Re: 1999 Mercuriser 454 air in fuel system

      Ayuh,... Welcome Aboard,.... Sounds like a vacuum leak, up-stream of the fuel pump,...

      Try a remote fuel tank to help diagnose where the problem is,...
      Any Grease is Better,..... Than No Grease at All.......


      • #4
        Re: 1999 Mercuriser 454 air in fuel system

        Air in the fuel system, has to be between the fuel pump and the tank. After the fuel pump, it's all pressure.
        Any of the lines from the tank to the pump are suspect, especially if they have the wide hose clamps on them.. You need the narrow mini clamps on fuel lines.
        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.


        • #5
          Sign up today
          Re: 1999 Mercuriser 454 air in fuel system

          If it has a water separating fuel filter, suspect that someone has overtightened the fuel line fittings in it. They end up with a hairline crack, and leak air into the fuel system....

          The world takes on a whole new perspective when viewed from 100' below...

          1972 Bertram 'Bahia Mar' 20
          2006 Mercruiser 4.3MPI (0W617679) w/Alpha 1 Gen II (0W829301)
          Please don't send service questions in private messages. That's what the forum is for. Messages of thanks, always accepted. :D
          Member of the month - April 2013. http://www.iboats.com/blog/achris-member-of-the-month/


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