# fuel problem with a 25 merc 2 stroke



## mark_gardner (Mar 18, 2009)

went out yesterday and had problems with my 03 merc 2 stroke  it wouldnt idle and when coming off plane it would die. if i wanted to restart it i had to choke it then once started i had to floor it, as long as i kept the throttle cracked at least halfway open it would run like a bat outta hell. i had it out about a month ago and it ran fine and the gas was fresh at that time so i'm not sure if i need a good cleaning or maybe a rebuild??? can anyone give me a ball park on the cost of a carb rebuild? guess i'll huff it over to the library to see if i can find the shop manual to see whats involved with a rebuild. thanks


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## Brett (Jul 16, 2008)

Carb rebuild kits on-line run $35 to $85
Get the OEM manual and DIY.
Take pics and post the process.
With all the E10 problems showing up, it'll be a popular thread.


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## tom_in_orl (Dec 9, 2006)

Sounds like the float in the carb is sticking closed. The cheapest way to go is to rebuild it yourself. Not sure on the cost to have some rebuild it but if you find the cost is 75% or more of buying a new one then I recommend getting a new one and install it yourself.


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## Brett (Jul 16, 2008)

New carb cost...$300 plus

http://www.crowleymarine.com

parts catalog link, left side of page


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## mark_gardner (Mar 18, 2009)

thanks for the quick reply guys [smiley=1-thumbsup2.gif] i think i'll spray a little carb cleaner in it, maybe try to run some seafoam thru it also to see what happens and if no luck then i'll go for a rebuild kit. the fuel tank and lines are less than 4 months old so i doubt i have any issues with them


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## B.Lee (Apr 29, 2008)

Diagnosing engine issues over the internet is a crap shoot at best, but I like to try!

Sounds to me like you have a clogged low speed (pilot) jet. The pilot jet supplies fuel to the engine at throttle settings of less than 1/4 throttle. Above then, the larger main jet comes into play and the pilot jet comes out of play. When you back down off the throttle, the pilot jet comes back into play. With a clogged pilot jet, the fuel supply is cut off, and the engine stalls. The choke on these motors isn't a true choke, but a primer circuit, and pulling it out shoots a small bit of fuel directly into the carb throat. the "choke" bypasses the clogged pilot jet, and the engine restarts.

While I would recommend completely disassembling and cleaning the carb, simply pulling the pilot jet and cleaning it will remedy your problem. Spraying carb cleaner in it or running seafoam through it will likely not do anything for your problem at this point.


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## mark_gardner (Mar 18, 2009)

> Diagnosing engine issues over the internet is a crap shoot at best, but I like to try!
> 
> Sounds to me like you have a clogged low speed (pilot) jet.  The pilot jet supplies fuel to the engine at throttle settings of less than 1/4 throttle.  Above then, the larger main jet comes into play and the pilot jet comes out of play.  When you back down off the throttle, the pilot jet comes back into play.  With a clogged pilot jet, the fuel supply is cut off, and the engine stalls.  The choke on these motors isn't a true choke, but a primer circuit, and pulling it out shoots a small bit of fuel directly into the carb throat.  the "choke" bypasses the clogged pilot jet, and the engine restarts.
> 
> While I would recommend completely disassembling and cleaning the carb, simply pulling the pilot jet and cleaning it will remedy your problem.  Spraying carb cleaner in it or running seafoam through it will likely not do anything for your problem at this point.


sounds good thanks, i have a feeling this is exactly whats wrong with it. hopefully it wont be raining when i get home this afternoon and i'll be able to pull it off and see what i can find. i'll let yall know what i find when i find it


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## TomFL (Oct 2, 2007)

Carb job is an easy thing to do, so go for it. Keep your parts separate and in order. It is not a big deal at all. 

If it'll help you I have a service manual for that motor. If you need help and have a fax I can fax down some pages for you.

-T


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## chrism (Jul 1, 2007)

> Sounds to me like you have a clogged low speed (pilot) jet.  The pilot jet supplies fuel to the engine at throttle settings of less than 1/4 throttle.  Above then, the larger main jet comes into play and the pilot jet comes out of play.  When you back down off the throttle, the pilot jet comes back into play.  With a clogged pilot jet, the fuel supply is cut off, and the engine stalls.  The choke on these motors isn't a true choke, but a primer circuit, and pulling it out shoots a small bit of fuel directly into the carb throat.  the "choke" bypasses the clogged pilot jet, and the engine restarts.


while it might be the carb, the merc 25 2 stroke only has 1 jet.


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## mark_gardner (Mar 18, 2009)

update on the carb***    took it off this afternoon and pulled some of the covers off, cleaned with carb cleaner spray then reassembled, fired it up and all indications are that its running like it should  [smiley=toast.gif]  one question though..... what  do i do with all these parts that are left over ?  ;D seriously though i do have one peice of linkage that has something to do with the fast idle adjustment so if anyone could help me out with that i'd appreciate it. i was going to haul it down to the local ramp and water test it but my brother called and wanted to bring his 3 year old son out on the bay boat and try cast netting for some shrimp so without much hesitation i agreed  wasnt to long into it his boy got stuck real good in the finger with a hook (all the way thru) so we had our hands full trying to remove it from a scared crying kid but we got it and he's doing fine,said he wanted to go fast so considering the circumstances i agreed, its a wonder how a high speed run at night takes your mind of the pain  btw, the shrimp are finally starting to show, i ended up with almost 50 of them , wasnt alot but enough for a small meal, the shrimp were pretty good size


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## REELKEEN (Mar 24, 2009)

Mark,
Sorry to hear about the motor issues. I've still got some shift issues with mine. 

Where did you go cast for some shrimp. I've always wanted to try.


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## mark_gardner (Mar 18, 2009)

> Mark,
> Sorry to hear about the motor issues.  I've still got some shift issues with mine.
> 
> Where did you go cast for some shrimp.  I've always wanted to try.


just started some random throws at the mouth of the ortega river, didnt bait them or anything just started throwing. the were good size and i expect them to get even thicker as the days go by. we were in about 5-6 feet of water


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