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Results 1 to 9 of 9
  1. #1

    Default 2007 25 hp Mercury will not run at wide open throttle

    I have a issue with my little 25 Merc, it’s a 2007 tiller manual choke 2 cylinder single carb model. The motor runs great a low speed but when you try to run WOT it bogs down. I have had the carb cleaned at my local marc dealer, changed the fuel line, cleaned the tank, changed the plugs, and changed the water pump, all of these things helped a little (maybe it sure starts easier) but it still will not pull WOT. I have checked the compression 116 lbs on both cylinders. I’m stumped any one have any sugestions?
    Thanks
    Vic

  2. #2
    Join Date
    Sep 2008
    Location
    Posts
    73

    Default Re: 25 Mercury will not run at wide open throttle

    Vic,

    I had a similar problem with my 25HP Merc, although it is a 1995 w/remote steering. It turned out the fuel tank vent was clogged and whenever I tried to run WOT, the carbs were not getting enough fuel. I replaced the old tank (it was pretty shabby anyway) and it fixed the problem.

    Dave

  3. #3
    Join Date
    Dec 2009
    Location
    Rineyville, KY, U.S.A.
    Posts
    217

    Default Re: 25 Mercury will not run at wide open throttle

    also check the fuel pump.

  4. #4

    Default Re: 25 Mercury will not run at wide open throttle

    I have the exact opposite problem with my 25 Mariner. It runs fantastic at full throttle but wants to die at low speed and idle. If I hold the choke out it will idle, but even when it's warmed up when I push the choke in it won't idle. Isn'y there an idle screw I can adjust to turn the idle up a little bit? If so where is it?

  5. #5
    Join Date
    Dec 2009
    Location
    Rineyville, KY, U.S.A.
    Posts
    217

    Default Re: 25 Mercury will not run at wide open throttle

    Ohnomark, sounds like your slow jet is stopped up. Clean and rebuild the carbs, and you should be good to go.

  6. #6
    Join Date
    Sep 2003
    Location
    New Tripoli, PA, USA!
    Posts
    12,436

    Default Re: 25 Mercury will not run at wide open throttle

    Try backing out the idle mixture screw 1/4 turn at a time and see if that helps.

    Jeff

  7. #7
    Join Date
    Jun 2008
    Location
    W.Monroe, La, USA
    Posts
    5

    Default Re: 25 Mercury will not run at wide open throttle

    Quote Originally Posted by ohnomark View Post
    I have the exact opposite problem with my 25 Mariner. It runs fantastic at full throttle but wants to die at low speed and idle. If I hold the choke out it will idle, but even when it's warmed up when I push the choke in it won't idle. Isn'y there an idle screw I can adjust to turn the idle up a little bit? If so where is it?

    Me too, was gonna ask that question but saw this 1st. Mine may or may not idle, but, it's real low.Can I add about 100 rpms? Thanks Dickey

  8. #8
    Join Date
    Dec 2009
    Location
    Rineyville, KY, U.S.A.
    Posts
    217

    Default Re: 25 Mercury will not run at wide open throttle

    just turn up the idle screw, but first, clean your carb.

  9. #9

    Default Re: 25 Mercury will not run at wide open throttle

    Had that problem with my 1985 model & it was a small crack in pickup tube in the fuel tank it finally got big enough that it would just die & I found it??? Hope this helps
    Can someone tell me what the timing is suppose to be set on??? THANKS

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