09 yamaha 25esh flooding

Perk_zk

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Jun 10, 2013
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Ive got an 09 yamaha 25esh 2 cyl 2 stroke that appears to be flooding the bottom cyl.
Carbs have been cleaned. Low speed jet was a little clogged. Looks great now. We took for a test. Basicaly the same results. I eventualy found that when i unpluged the gas line with the bowls full it would smooth out and take off like the day i finished breaking it in. I mean IMPRESSIVE!! until it started running short on fuel which i plugged line back in no punping the bulb. It would pick right back up for a bit the bogg down. Unplug the hose, smooths out and repeat all over again. Now the issue is what part is causing this? Originaly i thought the float needle was not closing so the fuel pump was just overfilling the carb. My dad pointed out to me that the pump gets its vaccum from the bottom cyl. I have since pulled both carbs. Examined the needle valves. They looked great to me and dad both. (Granted it dosent take much). Sooo out of curiosity i swaped the valves around. Reasembled and tested. Same results. I confirmed it is still the bottom cyl whe i pulle the breather cover off and a pool of gas was running out of the bottom carb throat. So would you think its the float needle, valve seat (fixed/pessed into these carbs) or something to do with the fuel pump. These floats are not made to adjust it is one plastic piece not metal like the old evinrude im used to working on. Any help would be appreciated. Looking around suggests none of these parts are cheap so itd be pretty nice to get it right the first time. Thanks
 

Perk_zk

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Re: 09 yamaha 25esh flooding

Update: a local mechanic suggested that on of the molded float may be warped. So we swapped the top for the bottom float have the same results basicaly. As the motor died/flooded itself out we watched gas flow back into the bottom carm throat.
Any ideas? Anybody?!
 

Toddboat

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Jun 13, 2013
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Re: 09 yamaha 25esh flooding

I'm by no means a mechanic, but here is my two cents...
It sounds like there is no vent on your fuel line, or that the vent it closed. On my boat, I have to unscrew the fuel cap when I prime the bulb, otherwise the fuel will not flow properly. By the same token, if the tank is not vented, there's nothing to stop the flow of fuel until air enters the fuel line which may only happen once your carb is flooded. Just a thought.
 

Perk_zk

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Re: 09 yamaha 25esh flooding

Thanks for your input buddy. I considered that as well. Especialy with these new EPA certified tanks that dont actualy have the vent hole. Buuuut with disapointment. We completly took the cap off today thinking maybe loosening it wasnt enough. But still the same results.
 

99yam40

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Re: 09 yamaha 25esh flooding

something is preventing the needle from closing off completely.

With carb off and bowl off turn carb upside down and try blowing into the fuel input to see if it is closing off. move the float around some

might be float binding on something simple.
hope you did not run something in the seat and damaged it
 

Perk_zk

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Re: 09 yamaha 25esh flooding

Thnks. I believe im gonna end up gettin a rebuild kit from sierra. Comes with new floats and needle valves. I really believe its prolly the float. Really hoping its the float. If it the seat for some reason thatl hurt a little bit. Ill post back with results.
 

perkdp

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Re: 09 yamaha 25esh flooding

What are the chances of having a pin hole in the fuel pump diaphram allowing the crankcase to flood ?
 

Toddboat

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Re: 09 yamaha 25esh flooding

I read on another website that sometimes a float can leak, allowing fuel into it. Once it gets fuel in it, it is too heavy to float. Something I never thought of before. If you remove the float and shake it, you can hear if this is the problem. Have you tried swapping out the float from another one of the carbs to see if it's the float itself? You mentioned doing this for the valves, but what about ruling out whether or not it's the float itself by swapping them?
 

Perk_zk

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Re: 09 yamaha 25esh flooding

Yesir we have swaped the foats too. No signs of fuel in the float.
 

Perk_zk

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Re: 09 yamaha 25esh flooding

Well dad put a float and needle kit in tonight. Said it dosent feel like the new needles are seatin all the way but either way he put it all in and together. Along with te fuel pump diaphram. Says its still not fixed. Says you can see gas bubble up theough the jet in the top carb once in a while.

Is there a way the plug behind the high speed jet could be leaking. Or an air port clogged up? We are about lost. Not sure what to do next.
 

Perk_zk

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Re: 09 yamaha 25esh flooding

Well dad put a float and needle kit in tonight. Said it dosent feel like the new needles are seatin all the way but either way he put it all in and together. Along with te fuel pump diaphram. Says its still not fixed. Says you can see gas bubble up theough the jet in the top carb once in a while.

Is there a way the plug behind the high speed jet could be leaking. Or an air port clogged up? We are about lost. Not sure what to do next.
 

perkdp

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Re: 09 yamaha 25esh flooding

Dad installed SIERRA Part #s 18-7837, 18-7838 and 18-7739. Anone want to share their opinion of SIARRA Parts ? Is there any float adjustment on this motor? Anyone want to share link, sync and idle mixture tips for this mortor ?
 

perkdp

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Re: 09 yamaha 25esh flooding

wow... first time i've been disappointed in this forum. is everyone ashamed to talk about their Yamaha outboards ?
over on the evinrude forums its like 100's of folks can't wait to answer your questions and try help.
 

99yam40

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Re: 09 yamaha 25esh flooding

1st you have to find a person with motor like yours
and then hope they have a service manual for it
and work on it themselves
and be on this site
and want to type out info out of their manual

Might be faster and easier to just get the manual yourself and read up

Hard to believe the seats are not replacable, but if that is true then it may take buying carb if seats are messed up.

I buy original Yamaha parts, so can not say one way or the other about the parts you bought and how well the work
 

Perk_zk

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Re: 09 yamaha 25esh flooding

Update: tested the boat again this mornin. Taking longer to flood now and will run WOT long as u dont start off flooded. A lot faster response from unhooking the gas line after its flooded and starts bogging down. Within just a couple seconds compared to prolly 10-15. I replaced the low speed jet plugs tonight with factory parts. I was not real shoked that it didnt fix the prob but they def needed to be replaced. When we had them off we did the old turn it upside-down and try blowing air trick. Both floats seem to touch the carbs but the bottom closes and wont let air through. The kinda acted funny at first then SEEEEMED to have sealed up and shut. Put em back on and sure enough with the motor runnin if u look in the carb with a flashlight u can see the highspeed jet bubblin just a bit of gas. Again there are no adjustments on these floats and they are brand new. Didnt see anything that suggests they are specific to top or bottom.
So my next plan of attack is leave the bottom carb alone and use the left over old parts to try and get a combination that will pass the upside down test with flying colors and see what happens. If i dont get the right combo i may try and modify one of the old ones and see what happens.
Ill keep yall posted.
Not to impressed right now with the whole molded float idea right now
 

99yam40

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Re: 09 yamaha 25esh flooding

post a pic of the floats, I would think there is a way to adjust as there are specs for float height on all I have seen.
But if they are aftermarket, Who knows what you would find
 

Perk_zk

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Re: 09 yamaha 25esh flooding

image.jpgimage.jpgimage.jpg

The brand new float i had already noticed that it sat below level with the carb. Believed the float to be hittin the carb b4 it actualy sealed against valve seat. Took a pic of the new and old float. Reinstalled the old float. It sits nice and level and dosent touch. Fixn to go test. I hope this is it
 

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Perk_zk

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Re: 09 yamaha 25esh flooding

CONCLUSION!!!: to answer perkdp's (dad's) concern on the non-yamaha factory parts. They are exactly that. Not factory yamaha parts. Dont know they are made by sierra either tho. They say made in tiawan with nothing connected to sierra other than the part number. The end result was that it was a needle valve all along best we can figure. After replacing the floats and needles the top carb was flooding. After closer inspection we noticed that the float seemed to be hitting the carb instead of resting and stopping on the needle. So we traded the old float back in and used the air flow test to check it. Then it looked to be sitting in the carb right and was also sealing against the seat. There was a dif in the floats u can see on the pics above wich was making the float bottom out b4 the valve. It is not flooding anymore and will run WOT as far as you want to go. After we got it goin we decided to adjust the throttle stop and see if we could make it run regardless of how far you back off the throttle. We have that issue fixed but created a little lag going from idle to throttle up. Just a little bit of tuning and i believe itl be like brand new.

Thanks for the input i got. Maybe this thread will help someone else in the end.
 

perkdp

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Re: 09 yamaha 25esh flooding

I'm quite disappointed in SIERRA parts this round. Bowl gaskets barely fit. Gas caused the top gasket (#11 in diagram) to curl up like a noodle and start splitting around the edge ovenight. Either the floats were wrong or the needle valves didn't match them. These floats are molded plastic. NO adjustment unless you can bend the plastic expect it to stay bent.
It now runs acceptible with OLD Floats, New Needle Valves, New pump diaphram, New bowl gaskets and one new top gasket.

does anyone have a video of doing a carb - link & spark advance & sync procedure ?
 

perkdp

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Re: 09 yamaha 25esh flooding

on the float pictures, the old float had a slope molded from mid to front. the sierra floats i was sent only had a dent in the middle so the float would hit the bowl b4 closing the needle completely. see pics if i can get them attached.
 

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