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  1. #1
    Member
    Join Date
    Aug 2019
    Location
    Jackson, Michigan
    Posts
    8

    2003 mercury 225 efi running bad

    2003 225 efi has a rough idle and loss of power on the holeshot. Today after running for about 10 min stopped and fished for about an hour started back up and felt like it was running on hald the cylinders at about 1500 rpms it clears up got up on plane and run it up to 65 mps came off plane back idle and idled like it always does after 30 sec or so it starts running very bad and stalling this time i had to give it throttle to keep it running. and every so often it will backfire on cold start up it has been to several different mechanics and they keep telling me that nothinh is wrong or the tps was out of adjustment but from what i understand is that there is no adjustment on the year motor. now all cylinders are 128 to 130 psi. fuel pressure is steady at 42 psi. Fuel system has been all gone threw cleaned new hose primer bulb. new plugs ans wires. Mechanic said that theres no code in computer tps is now reading right map sensor is reading coolant and air temp sensors all reading corectly. and the timimg is right also. myself and the mechanic have inspected all the engine wiring looking and use a meter to find a broken wire loose connection and coils have all been tested also.

  2. Member
    Join Date
    Aug 2019
    Location
    Jackson, Michigan
    Posts
    8
    #2
    Also has new fuel injectors and reeds

  3. Member
    Join Date
    Dec 2013
    Location
    Spring Hope,NC
    Posts
    7,252
    #3
    Check your reeds. They will make it do some odd stuff at idle.

  4. Member
    Join Date
    Jun 2013
    Location
    LONGVIEW TEXAS
    Posts
    13,917
    #4
    all sensors need testing to verify working correctly
    .................................................. ...the scariest thing in life is the unknown ...................................

  5. Mercury 3L/4 Stroke/Verado Moderator EuropeanAM's Avatar
    Join Date
    Apr 2008
    Location
    Greenville, SC (US)
    Posts
    94,834
    #5
    If you need further assistance, your engine is covered in the 3L Forum (two more forums down the list).


    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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