Yamaha 2007 25msh 2 stroke

[Fishfinder117]

Sooo, I have a 25hp 2 stroke and it starts and idles fine. But when I turn the tiller handle to the point the mechanism pushes carb butterfly it seems to just flood out to the point it will stall. I have cleaned the carbs multiple times, replaced coil packs, rebuilt fuel pump, replaced fuel tank and fuel lines, new plugs, compression test on both cylinders. Does this sound like maybe cdi box? Looking for any help

 

[Sea Rider]

Welcome to IBoats,

Is that a single or double carbed motor ? Does the motor stalls when shifting forward from neutral/idle or just when on its way forward, how about when throttling much more than previous ?

Happy Boating

 

[Fishfinder117]

It is double carbed. Idles fine shifts into forward and reverse fine. I can get enough speed out of it to get on plane running like 8th of the throttle. But if I go over that it just stumbles and seems to load up and stall if I don't back back down to idle on tiller handle. If i free rev it in driveway, it just never seems to clear out either

 

[Sea Rider]

When the motor loads up before stalling when throttling way more does the revs go way high ? Revving any motor at neutral, idle, fast idle or even way more means nothing, the issue is when running at load, that's powering any boat running geared at speed. What about priming the bulb firm when begins to stall, will the motor keep revving higher without stalling?

Troubleshoot all fuel related firstly, have clean fuel tank and all fuel filters, fuel pump's diaphragms are in flexible, not extremely ballooned, fuel hose connectors still have flexible o'rings, if hardened will let air in and motor will miss, stalls when 1/2 to full throttle is applied, motor will recuperate its rpm when throttling down.

Happy Boating

 

[Fishfinder117]

No it doesn't rev up high, it will just stall out if I give it more throttle. Tried to pump bulb while testing it out on the water and it didn't help any. It seems that as soon as I turn handle and the mechanism slider hits the butterfly connection it stalls. I had replaces and went over all fuel components and came up with nothing. Is there anyway to check cdi box? Maybe stator is bad and not getting enough spark? That's about the only 2 things I can think that's left that wasn't replaced or rebuilt.

 

[Fishfinder117]

Should say stumble first before it stalls out, I can back out of the throttle and most the time will go back to idleish speed

 

[QBhoy]

Get the carbs off it and cleaned. Check the Diaphragm. Make sure the main jets are clear. A wise man once told me that 9/10 times that a 2 stroke merc or Yamaha motor gives you trouble...it’s carb related. Forget everything else until that’s been ruled out. He hasn’t been wrong so far, with my engines. You can go down a horrible twisted path of despair if you start thinking could, cdi or otherwise first. See what a good carb clean and strip does for you.

 

[Fishfinder117]

Carbs have been cleaned multiple times. As stated in first post all carbs where cleaned, new fuel lines, fuel tank, rebuilt fuel pump, spark plugs, coil packs. I have cleaned a 1000 carborators in my day, I know they are cleaned when I'm done with them. And with 2 stroke, it's fuel, air or spark. Wanted to know if there's a way to check the cdi or the strength of spark along with stator.

 

[racerone]

Does spark jump a gap of 3/8" on a test device , yes or no ?----We read it here all the time----" cleaned the carburetors 4 times and motor still runs the same " ------Proves that it is not a carburetor problem.-----Checked the reed valves ?-----Done a compression test ?----Made sure throttle plates do not open too early ?----Checked flywheel key ?

 

[Fishfinder117]

Not sure I'm following on jumping spark 3/8". Pulled reed cage out other day when I cleaned the carbs again and everything looked fine. Did a compression test too and all up to specs that are inside of hood. I have not checked flywheel key tho and am going to look into it

 

[Sea Rider]

Never seen a key go wrong unless highly corroded if being made with other materias than SS ones which are the ones found in Yam motors. Take advantage to check with a tester the ohm impedance of the exciter coil. If carbs, compression, spark is strong seems it's an electrical related issue. To troubleshoot it right will need a Service Manual, instrumentation to check all electrical components values each electrical component works with, that's resistance with engine OFF and voltage while pulling thre rope or with electrical start.

Won't say much if any one of them heats up while motors works under load, cools down, starts to heat up and so on. Erratic electrical condition is the hardest to troubleshoot right unless having at hand all electrical components to swap and test till the culprit is found. It's a bad and costlly procedure to swap all non electrical components prior troubleshooting all electrical ones..

Happy Boating

 

[QBhoy]

Carbs have been cleaned multiple times. As stated in first post all carbs where cleaned, new fuel lines, fuel tank, rebuilt fuel pump, spark plugs, coil packs. I have cleaned a 1000 carborators in my day, I know they are cleaned when I'm done with them. And with 2 stroke, it's fuel, air or spark. Wanted to know if there's a way to check the cdi or the strength of spark along with stator.

Sounds like you’ve been really unlucky with carbs over the years. 1000 carb cleans you say ? Are you sure you’re doing it right ?

 

[Fishfinder117]

Well I kinda figure there would be one guy where I would have to explain.... I have cleaned 1000s of carbs over my time, maybe not why you think... maybe it's because I race cars that use methanol and if you know anything about that fuel is that you must clean it evrytime it goes threw the carb... everytime!! Hope that clears up why I know my carbs are good. Way to go for being today's "guy"