2003 mercury 25hp 2-smoke acting up

Discussion in 'Outboard Maintenance' started by Flyline, Nov 20, 2008.

  1. Flyline

    Flyline Won "Do More With Less" Award!

    I have a 2003 25hp merc electric start 2-stroke, I haven't been using it for awhile but been giving me problems ever since.

    I replaced spark plugs, fuel filter, gear lube, carb cleaned out, adjusted timing and check fuel lines and everything went great.

    Plm is motor start right up but little rough and giving it power off it go. Soon it reach 3500 RPM then it bog down and kwit! I replaced impeller peeing went great.

    Start up again then try again up to 3500 RPM then stalling begin to run very rough.

    What's up with this motor??

    This motor has about 500 hours on it.
  2. Gramps

    Gramps Living & Dying in 3/4 Time

    Sounds like a carb rebuild time. That is the range of the high speed jet; could have varnish blocking the itty bitty hole.

    It really is a simple process, my '01 Merc 25's carb is sitting on my kitchen table waiting to be rebuilt tonight. Took a little over an hour to pull the carb, disassmble & clean. Mine was sitting for 3 years before I bought it and did have some varnish in the bowl.

    A rebuild kit is $55, but it has every single screw, spring, gasket, jet, etc. that you need for the carb & fuel pump. Search for the old post with the "free manual" to find the Clymer's for your engine, if you don't have it.

  3. Flyline

    Flyline Won "Do More With Less" Award!

    Thanks, I hope u didn't stink up the whole house up by left the carburator on the KITCHEN TABLE!

    I was thinking it might be the jets.....
  4. Gramps

    Gramps Living & Dying in 3/4 Time

    Glad I could help. Ya it kinda stunk up the house, but I'm single so it's no big deal.

    If you want to buy online, boats.net has a good selection of parts and ships quickly. Gotta replace the starter & water pump also. One question for you, do you have to replace the drive shaft seal when you change the water pump? Read somewhere you did...
  5. Flyline

    Flyline Won "Do More With Less" Award!

    yes, reason why I did it is because the seal getting worn out, so I better off to get a new one ;)
  6. islander1225

    islander1225 Well-Known Member

    my 98 25hp 2-stroke was doing the exact same thing when i bought it , so i mad sure i had fresh gas for it changed the little filter that is under the cowling and sprayed a whole can of valvetec decarb in the motor and it has run like a champ since then not a single prob.

  7. captnron

    captnron Guest

    It's trying to impersonate a Yami. ;D ;D ;D ;D ;D

    JK, I'm with the rest - Carb. ;)
  8. Flyline

    Flyline Won "Do More With Less" Award!

    ;D ;D ;D ;D sureeee!!!!!! I ned my NIB 25hp yami LS to breakn in but maybe next year! :-/
  9. Aquaman

    Aquaman It'll feel better after it quits hurtin...

    I learned a trick from a guy that was a Ferrari mechanic. Those things have more carburettors than wheels. He would take broom straw and use it to clean the jets. Regular yellow broom straw, the natural kind. He said that it doesn't hurt the jets and its tappered so it will clean the edges real well.
    He'd break a piece off the broom and trim it to the size he wanted. Being dry and a natural material it scrubbed the tiny holes real well.