motor dies when going from forward gear to neutral

i have a 1985 25 hp mercury 2 stroke. been working on this motor for a couple weeks now trying to get it to run right. the motor will some of the time not stay running when i take it from forward gear into neutral, if i do it very slowly and carefully i can get it to stay idling in neutral and it runs just fine but it will bog down very bad and is obvious that it is about to shut off and it just all the sudden picks back up and starts idling. the times that it does shut itself off, when i go and try to start it again it is a pain in the butt. doesnt even try to start (pull start) i have to mess with the throttle cable to get it started and even then its a pain. would appreciate any help guys im tired of stressing over this. thanks

from what ive found searching google maybe my lower unit shift rod thing might be messing up? i dont think it is a carb issue because it was rebuilt in february. maybe carb needs adjusting but idk

From what I gathered searching for this problem something with my shift cable isn't adjusted right, anybody know anything bout these mercs?

Sounds like the butterfly is shutting completely flooding the engine. Does it idle kinda slow? If so try adjusting the idle screw a little to open it up. Problems like that sure can frustrate a fella fast.

MtDewMadMan said:

Sounds like the butterfly is shutting completely flooding the engine. Does it idle kinda slow? If so try adjusting the idle screw a little to open it up. Problems like that sure can frustrate a fella fast.

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yes it did idle very slow until i adjusted the screw near the throttle cable so that it would rev the engine slightly to idle faster. is the idle screw your talking about the one i adjusted or is it the screw on the carb? i really need a manual lol

Without seeing it all I can do is guess here.
But it sounds like you may have inadvertently adjusted the fuel jet instead. I would take the cover off and turn the throttle. Watch what moves. Depending on what brand/model your engine is will determine where the idle screw is at. Take some good close up pics of it and post them if you can and we'll go from there. Fishing seasons here and we need to get ya on the water :lol:

Your best bet is to get a manual.I work on Mercs & their pretty easy to work on as long as you have a manual & some mechanical knowledge. :wink:

Was half asleep still on the previous post. Yes that's sounds like the idle screw. Try adjusting the one on the carb in 1/4 turn at a time. Keep track of how many turns you go so you can always put it back where it was to begin with if need be. Don't go too lean though it won't get enough oil mix to lubricate correctly and could cause a ton of damage.

crazymanme2 said:

Your best bet is to get a manual.I work on Mercs & their pretty easy to work on as long as you have a manual & some mechanical knowledge. :wink:

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If you've done any carb adjustment and he can't find a manual I'm sure he'd appreciate any troubleshooting advice you may have to offer on the subject.

Please check to be sure you have spark on both cylinders, then after running it, check the plugs to be sure they both look alike and are burning the fuel. You might see a difference in the way they look.

thanks guys, i do have spark in both cycl. and i changed the plugs the day before i took it to the lake and when i came back i checked them again. they still look good. one thing thought i didnt gap them like ive heard your supposed to do i just took them out of the box and installed them.

Those engines had a surface gap plug originally, but there is an NGK electrode plug that's a recommended change over. Never trust the plugs out of the box.

The reason I mentioned looking at the plugs and making sure they're firing in the cylinder, is I've got one with great spark, compression, and fuel to both cylinders, but the top cyl won't show that combustion is occurring in the cyl. I won't hijack this thread to explain it all, but I've got a good running 85' 25 XD.......On only one cylinder.

I tried this with my Yamaha today. If the fuel line is connected to my tank in the wrong direction I can get it to start. But after a run it stalls out and is impossible to restart it. Maybe yours is accidentally on backward ? Just a shot in the dark lol.

just thought id let y'all know what i found out, the float in the carb was trashed and filling up with gas. turns out it wasn't stalling when going from gear to neutral but it was flooding out every time i slowed down. mechanic replaced the float and no more stalling and flooding.