Excessive smoke at start up

[Strat_Yamaha250]

why would you get banned? For taking the time to explain to me how my motor works? I really appreciate the info and I wanted the manual for my own benefit. It does me no good to know how something works if I can't see a diagram or schematic to take it apart, that's what I get for being an engineer. I certainly wasn't questioning you or your advice. Thank you for your time and I'll certainly try everything you have told me.

[99yam40]

Can you recommend a good manual I can buy for the inner workings of this motor. You have definitely given me some more places to look. I went to the Yamaha home page and have been looking at there diagrams but I would like to buy a manual so I can have it to use while working on the motor. I saw on there homepage where you can purchase a Yamaha manual, I just want to make sure I get the right one.

Thanks for all the help.

The Yamaha one is good but I do not know if it will give you that info you are looking for . The Yamaha techs use it and already have the basic knowledge of the motors and systems. It will give all the specs and step by step instructions on
testing the specific motor you buy it for. It took me awhile to get used to it, you know how that goes sometimes with things that are translated to English but I like it now.
Some like the aftermarket ones because they say they explain things better for people that do not have all the knowledge already, I do not know as I have not picked up an aftermarket one yet. There are places on line that you can download manuals for $10 or close to that. I am not saying they are what you are wanting or needing but if they are not the you can always pick up a Yamaha hard copy one from a dealer or Yamaha site online and $10 is no big loss if you are not happy with it. Send me a PM and I will try to help you find some of the sites if you would like. There are part breakdown pics on the part places and in the manuals to help

[99yam40]

why would you get banned? For taking the time to explain to me how my motor works? I really appreciate the info and I wanted the manual for my own benefit. It does me no good to know how something works if I can't see a diagram or schematic to take it apart, that's what I get for being an engineer. I certainly wasn't questioning you or your advice. Thank you for your time and I'll certainly try everything you have told me.

Some times the moderators will not like the way some one says things or some one will not like it and report it to the mods and off you go

[Strat_Yamaha250]

It's just text, he didn't offend me in any way shape or form and I certainly hope I didn't offend him. That was not my intent. He's too smart to be banned from this site, he is a valuable asset here or any forum he is on. You can tell he knows what he is talking about.

[mitch]

what is happening when you turn off your engine the unburnt petrol you call it ( gas ) evaporates from inside the motor and to a certain extent in the vst but it leaves the oil behind as that does not evaporate as easy.

So the next time you start your engine that residual oil is burnt, so instead of getting 50.1 it is more likely 25.1 or higher that is where the smoke is coming from .

[rodbolt17]

what mitch says.
if nothing is wrong with the engine thats kinda how two strokes work.
smoke at start up is common with carbed and EFI engines.
the VST on that 3.1L holds about 1 qt of gas.
the oil is mixed at the VST from the oil pump.
so your happily buzzing down da lake.
zip up to the ramp, you have just made a 20 minute high speed run and the oil pump has been mixing the gas at the VST at 50/1.
you idle for 3 minutes to get it loaded on the trailer.
your still burning that 50/1 mix not the 120/1 mix it idles on.
let the engine sit and the fuel left in the crankcase starts evaporating leaving the oil behind,at the next start cycle not only is the oil left behind burned but the VST is still supplying fuel/oil at 50/1.
makes it smokey smokey.
now if you have a contaminated O2 sensor OR a popped fuel pump diaphram the symtoms will be loss of top end power and it smokes ALL the time not just at start up.

[rodbolt17]

as far as manuals go.
none actually do a decent job of describing HOW the system works.
however its a simple speed density EFI setup just like many automotive EFI setups.
only this one runs the O2 sensor in an oil bath .
and this one does NOT monitor the O2 sensor for inccorect feedback.
this one an incorrect feedback can actually blow a piston.
but if you google speed density EFI you can get some decent reading.

[Tucker]

Ok Strat, I guess you figured out that you're not going to get a hug from Rodbolt. Extremely sharp guy, I've been following his posts on other forums for a long time. I strongly suggest you get the official Yamaha shop manual; parts.net is a good source. You'll drop about $100 but it's worth it. It's good for identifing parts and understanding the sequence of assembly. As far as diagnosing a problem like you have, forget it. Put the book in front of you when you read the posts and what's said starts to make sense. Hacks like us are very fortunate to have guys like Rodbolt, boats.net, and 5 or 6 other guys that frequent this forum. Usually highly skilled tech guys have little patience with us knuckle bangers.

[rodbolt17]

its not that I dont have patience, its that I do this every day and sometimes quit realizing that I have 30+ years doing this and I may have seen a bit more and have a bit more practicle training.
however if you have an issue with your yamaha I will,as others, try to help.
most of my experience is with V6 twins and 150-F350.
we dont see many small motors.
a smattering of V4 and inline F motors and a few 40's.
8-10 25's and a hand full of the tiny mites.
one large difference in this 2 stroke OX66 VS an EFI four stroke is the lack of an ISC(IAC to most) valve.

[Strat_Yamaha250]

Problem is fixed!!! Apparently the last shock treatment I ran with Ring Free worked real well. We pulled the plugs out again after running it at various RPM's in the water. There were very small carbon fragments around the electrode on all of the plugs. We also found some debris in the VST Filter and cleaned it and put it back together. One of the three low pressure fuel pumps was not working properly so we went ahead and replaced all three pumps since they are nearly 7 years old. The massive smoke is gone and the loss of rpm's at WOT is gone as well.

Thanks to everyone that chimed in on this! I really appreciate all the input and direction.

[Ranger205vs]

2002 Yamaha 225 smoking and fouling plugs

I have a 2002 Yamaha 225 3.1 ltr outboard that has excessive smoke at start-up and sometime when idling. I have put numerous sets of plugs in it and it continues to foul them. I was curious if the fuel/oil mixture is running too rich and if there is a way to adjust this. Please help, it seems like I am having to work on this motor all the time. Any suggestions would be appreciated.

[Tucker]

Could be a bunch of things beginning with adjustments to the oil injection linkage. Out of adjustment usually goes to rich. Lots of threads here, including some pics I believe, about how to adjust it. Not sure why you have to work on it all the time. Yea, they are sensitive to routine maintenance and clean fuel, but dedicate a little time to maintenance and they are pretty trouble free. They also have a few quirks that are detailed very well on this forum and THT.

[rodbolt17]

ranger
instead of hijacking a 3 year old post.
try this.
start a new thread.
post the model number and a description of the issue.

then there is less confusion.