# HELP!!! 90 yami 2 stroke



## hawaiifly (May 28, 2011)

I got a 97 yamaha 2 stroke and the 2 bottom cylinders are not firing. There's spark and fuel, maybe to much fuel and its flooding the cylinders. Any advice please. Thinking of repowering to a new etec? :'(


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## Creek Runner (Sep 1, 2011)

Compression test needs to be performed. 

Standing by


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## hawaiifly (May 28, 2011)

I took the carbs to our local yamaha dealer and they said that the middle carb needs to be replaced and the bottom carbs needs a new diaphragm. They said that its the reason why the middle and bottom cylinder are flooding and not firing. They blamed it on my fuel system saying its dirty. I just put that engine on my boat 2 months ago and my previous 115 did not have a issue.


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## danville_marine (Jan 24, 2013)

my bottom cylinder wasnt running on my 40 yamm the choke diaphram had split and flooding it on order now


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## Creek Runner (Sep 1, 2011)

> I took the carbs to our local yamaha dealer and they said that the middle carb needs to be replaced and the bottom carbs needs a new diaphragm. They said that its the reason why the middle and bottom cylinder are flooding and not firing. They blamed it on my fuel system saying its dirty. I just put that engine on my boat 2 months ago and my previous 115 did not have a issue.


Your bottom carb doesn't have a diaphragm, and just to be clear in 15 years of working on Yamaha's 2-stroke I have only came across maybe 3-4 carbs that were Na to the point of being replaced. Not saying its not bad just rare.


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## cutrunner (Jun 8, 2010)

Yea the only carbs I ever had to replace were on motors that got dunked in saltwater or sat with water in them for a period of time.


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## Creek Runner (Sep 1, 2011)

> Yea the only carbs I ever had to replace were on motors that got dunked in saltwater or sat with water in them for a period of time.


Yeah I'm not even talking about those, just the ones I have cleaned 3-4 times and couldn't get right. 

I had one with a little piece of metal in the chamber of the carb 115hp 2-s I could see it with a flash light moving around but for the life of me I couldn't get it out. Replaced it under warranty after several photos to tech support for authorization. Didn't have to send it back so I drilled that sucker out just to say I got it out, lol even though the carb was done at this point.


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## hawaiifly (May 28, 2011)

I find it kind of odd as well. I bought the engine used and had it for 2 months. It ran good. They said there was a broken piece in one of the carbs and that's the one that got to be replaced.


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## MariettaMike (Jun 14, 2012)

> I find it kind of odd as well. I bought the engine used and had it for 2 months. It ran good. They said there was a broken piece in one of the carbs and that's the one that got to be replaced.


There aren't many moving parts in a carb that can break other than the float hinge or float valve. If the float breaks it will flood.

99% of carb problems is crud blocking one or more of the passages within the carb.

Ask the shop to show you the broken part(s). You should be able to buy just the parts that are broken.


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## Creek Runner (Sep 1, 2011)

> > I find it kind of odd as well. I bought the engine used and had it for 2 months. It ran good. They said there was a broken piece in one of the carbs and that's the one that got to be replaced.
> 
> 
> There aren't many moving parts in a carb that can break other than the float hinge or float valve. If the float breaks it will flood.
> ...


If that happens when you pump the primer bulb gas will run out the front of the throat.


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## hawaiifly (May 28, 2011)

I need some serious help guys. My engine still is not fixed! The shop has to replace the middle carb because a piece of metal broke in the carb, and the other 2 are being rebuilt. My question is the shop is charging me $581 in parts and $191 in labor. I went to boats.net I can get all new carbs for less. Is it difficult to sync carbs on this engine?


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## Creek Runner (Sep 1, 2011)

> I need some serious help guys. My engine still is not fixed! The shop has to replace the middle carb because a piece of metal broke in the carb, and the other 2 are being rebuilt. My question is the shop is charging me $581 in parts and $191 in labor. I went to boats.net I can get all new carbs for less. Is it difficult to sync carbs on this engine?


No they are not difficult, pretty simple if your mechanically inclined. You could also buy the new parts put them on and if you have a hard time with the sync just pay the shop to sync them. 

I looked up your parts as well and your looking at $700 +\- by the time you buy all 3 carbs, gasket o-rings, and shipping.


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## hawaiifly (May 28, 2011)

yeah just looked at boats.net. I just need the carbs and the O-rings on the intake. Its 681.00 with shipping. The Yamaha dealer is charging 772.00 they are rebuilding the 1 and 3 carburetor and replacing the center. I can get 3 new ones for less. I would like to think I can sync, I am a journeyman heavy truck tech. : Just need some instuctions. ;D


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## hawaiifly (May 28, 2011)

I got my boat back from our local yamaha "stealer" they replaced the middle carb and rebuilt the other two. The only cylinder that is firing is the middle the one with the new carb. The other rebuilt carbs are not firing, the dealer said they were too far gone to be rebuilt. I have two carbs coming in but I find it really odd that they rebuilt two carbs and both of them don't work? Where is that enrichment lever supposed to be normal or closed? I just want my boat to run again!!!


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## Dillusion (May 21, 2012)

The enrichment lever has 3 positions. There sticker on your carb intake cover should tell you the settings and positions. One is open, one is closed, and one is normal. For regular operation it should be on normal at all times.


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## cutrunner (Jun 8, 2010)

Sorry to hear about your bad luck so far.
Why did you take off a perfectly good running 115 that was paid for again?


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## hawaiifly (May 28, 2011)

I do regret taking off that good running 115 now. The reason I went with the 90 is that it is a lighter engine. I got better draft with it or I felt like it did. As far as the enrichment lever being in any other position besides normal what would it do to the engine?


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## hawaiifly (May 28, 2011)

The strangest thing happened, I got two new carbs the top and the bottom carbs in from boats.net I pumped my fuel tank out put 5 gal. of non ethanol gas and a bottle of sea foam. I noticed the enrichment lever was set to the closed position so I flipped to "normal", primed the system and it started and seems to be running fine. When I picked it up from the shop it was only running on one cylinder and even the shop was sure that I needed to replace the other two carbs. I'm gonna wet test it tomorrow after work for the real test. Any of you Yamaha gurus know what is going on!?


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