Yami 9.9 starting problems.

[Hoghunter]

I have a 2009 Yamaha 9.9 High Thurst. Has ran like a top until this past weekend. It had been sitting for about three weeks and when I went to start it was a bear to start. It sputtered and farted and sounded like crap when it finally fired. After sputtering for a bit it will all of a sudden catch and rev up to say 3500 or 4000 rpm. After it's warm the behavior seems to leave.

I've went out the last three days and the same behavior. I will turn it over numerous times before it fires and then it will sputter like hell and then all of a sudden catch and rev up to where it should be based on my throttle position. If I back off to much it will kill and then take a couple of times again to start. Here again though once it's ran for 10 minutes or so then it has normal behavior. You can turn it off and on and it starts just fine and will then run without sounding like a moped.

I know the problem is with the carb but not sure if it's choke or internal carb issue. Any thoughts or has anyone else had similar problems and got them diagnosed?

[tomictime]

similar a few seasons back jeff, i fixed it w carb cleaner

[MegaByte]

Welcome to the world of ETHANOL! If you use gas from a station on land vs one at a marina, you are another victim like me of ethanol contamination. It literally will eat rubber and plastic fuel lines, gaskets and is a pain. It can also cause a failure of the pump bulb. I had similar issues with my 25 Johnson. You are one of thousands of people across the USA complaining about the effects of this crap. The Oregon State Legislatiure passed a law effective Jan 2010 that will allow us boat motor owners to buy premium grade fuel without ethanol in it. Ethanol is not oly corrosive, it absorbs water. Yet another non friendly motor causing problem. I am not a mechanic, and this is only my suggestion based on my own personal experience this past year on my Johnson as well as my two Hondas. It may be another problem you are having, but i suspect ETHANOL may be the issue.

[Onokai]

Star tron in the gas keeps this from happening . It counters the ethanol-I run it in all my motors except cars.
Mark

[foxer]

My T8 did the same thing. Took it in and had the carb cleaned. Runs great now. Dealer said it was the ethanol that sat in there. If you have to run ethanol, they suggested stabilizer and drain the carb after use.

[KingSlew]

Ethanol!

[gerberman]

The other thing to check is the key in the flywheel, I had a similar problem, took it to three different shops to finally find the broken .25 cent key, fixed it and it runs like a top, now in Alaska for a kicker. Gerberman

[Reel Song]

Might want to check the oil also, Last year mine was doing the same thing and when I checked the oil I found the crank case full of gasoline, fuel pump was leaking into crank case. I drained oil , changed fuel pump and no problems since.

[croation2]

Originally Posted by gerberman

The other thing to check is the key in the flywheel, I had a similar problem, took it to three different shops to finally find the broken .25 cent key, fixed it and it runs like a top, now in Alaska for a kicker. Gerberman

[Spindrifter]

My 2002 6hp Yamaha kicker is also giving me fits. It will start fine (choked) but won't really run at all at lower rpms unchoked after warmup. I took the carb apart and cleaned everthing really well with carb cleaner and there didn't appear to be any varnish inside. Put everthing back together and still have the same problem.

[gerberman]

It only takes a few minutes to check the flywheel key, do not just look at it, take it apart. if it is in pieces, replace. then everything should work fine. Don't ask me how I know.

[tomictime]

ah so, another bit to add to the spares box..
thanks

Originally Posted by gerberman

It only takes a few minutes to check the flywheel key, do not just look at it, take it apart. if it is in pieces, replace. then everything should work fine. Don't ask me how I know.

[Hoghunter]

Thanks for all the suggestions guys. I pretty much heard what I thought I would hear but it's always nice to at least see what other's have experienced.

I'm going to start with checking the flywheel key. Then move to cleaning the carb.

I know it's not gas in the oil as I had that happen to my T8 a few years ago and when this one started acting up that's the first thing I did was check the oil. All good there.

I put a lot of hours on this motor. Had it a year and have 446 hours. I need to make it a habit of running out the gas from now on as I know that it's not good to let the fuel sit in them especially once it starts to get cold.

[pirk fan]

My 1995 T9.9 has had carb problems over the years too. Several rebuilds, and the solution seems to be not just running the carb dry, but also removing the drain screw and fully draining the bowl. I'm also draining the fuel line into a designated jar before starting it, suspicious that fuel sits in the line and bulb and degrades. Very few problems since doing this after last rebuild.

Originally Posted by Hoghunter

Thanks for all the suggestions guys. I pretty much heard what I thought I would hear but it's always nice to at least see what other's have experienced.

I'm going to start with checking the flywheel key. Then move to cleaning the carb.

I know it's not gas in the oil as I had that happen to my T8 a few years ago and when this one started acting up that's the first thing I did was check the oil. All good there.

I put a lot of hours on this motor. Had it a year and have 446 hours. I need to make it a habit of running out the gas from now on as I know that it's not good to let the fuel sit in them especially once it starts to get cold.

[Hoghunter]

Originally Posted by gerberman

It only takes a few minutes to check the flywheel key, do not just look at it, take it apart. if it is in pieces, replace. then everything should work fine. Don't ask me how I know.

So you're saying that the flywheel needs to be removed to check the key? Is this a shaft key you're referring too?

I've removed and cleaned the carb and that changed nothing. Still runs like a moped and sputters and farts.

[gerberman]

Originally Posted by Hoghunter

So you're saying that the flywheel needs to be removed to check the key? Is this a shaft key you're referring too?

I've removed and cleaned the carb and that changed nothing. Still runs like a moped and sputters and farts.

Yes, just pull the wheel and it is the key that keeps the shaft and wheel aligned, this equals timing correct. Gerberman

[Pilar]

My 2004 T25 Yamaha gave me fits until I started storing it dry, no fuel. The fuel dries out and the leftover stuff plugs small passages in the carb.

On the T25 there is a plate on the top of the carb held on by a few screws. There is a gasket under that with some channels in the top of the carb under that. On the second or third carb expedition I took this off and under the rubber gasket I found some powdery white stuff. This can be remove with a soft brass toothbrush and some carb cleaner. Squirt some through whatever holes or passages you find using the little plastic red hose taped to the can.

On other carb expeditions I found the accelerator pump was sticking and would not return to the up position. Bottom line is either avoid 10% ethanol fuel or run the fuel out of the engine before it sits for any length of time. With the engine warmed up, remove the fuel hose from the front of the motor and let it run out of gas. This will take a while. Then open the bowl drain screw. It is also helpful to use the blue Stabil that is for the ethanol fuel.

Ethanol seems to effect anything made of flexible plastic like the fuel pump bulb on the fuel hose. The plastic gets hard and cracks.

[ripnlips1]

Clean the carb before you start taking it apart. Buy a can of GUNK carb cleaner, start the kicket and spray the carb cleaner into the carb and stop just before it stalls. Do this a couple of times. If that doesn't fix it then move on to the other recommended things. I have a 2002 9.9 and this fixed the same problem for me.

[Hoghunter]

I tried the carb cleaner already that was done before I ever pullled the carb off. When I pulled the carb I sprayed a good amount of cleaner through every little orifice I could find. Honestly the carb looked very clean inside. I seen no residue anywhere. The thing looked new inside.

I've double checked the oil again and it's clean so I know the problem isn't the fuel pump leaking into the crankcase.

I've changed out all my filters.

I pulled the plugs they were pretty fouled and replaced with new. None of the above has changed the behavior one bit.

The only thing left based on suggestions I've seen is to pull the flywheel. Somehow that seems a bit more of a job than a few minutes. I'm trying to figure out now how to hold the thing so I can get the nut off without buying the flywheel tool from Yamaha.

I'm also wondering if I should have let the carb soak in cleaner when I pulled it versus just spraying it out.

This is frustrating as I've never had so much trouble getting one of these Yami's back to normal again.

[KingSlew]

Is your motor a 2 stroke or 4 stroke?

[Hoghunter]

Originally Posted by KingSlew

Is your motor a 2 stroke or 4 stroke?

4 stroke.

[KingSlew]

I think it has to be fuel mixture related. If it was timing it wouldn't smooth out after it warms up. I presume you've cleared the air cleaner, have the plugs gapped correctly and have drained and cleaned your fuel filter and bowl. Did you say that you rebuilt the carb? All new gaskets? Could you have an intake leak?

[MattPark]

The 4 strokes (and small motors in general) have some seriously small ports in the carburetors. Pulling the carb off, the float bowl off, and cleaning all the ports and jets with high pressure canned carb cleaner should be a yearly maintenance item. The accelerator ports in particular can be long, are very small in diameter, and are easily clogged.

With the small amount of fuel these engines use, a lot of the debris simply sits in the bottom of the float bowl (as opposed to quickly being pulled through in a higher fuel consumption scenario). Cleaning that stuff out before it becomes an issue is a good idea as well.

[Hoghunter]

I'm going at it again today and see what happens. I thought I sprayed all the ports with the carb cleaner the first time. When I took the float bowl apart on Friday there was no debris in the bottom and it looked clean. The whole carb looked clean so if it's the carb then it has to be one of the ports/jets being plugged. Them things are so darn small you can't tell.

As of yesterday the symptoms were still the same it would start and run like crap and then all of a sudden it catches and runs very normal. If you then back off the throttle and try to accelerate again it will then repeat the same scenario. It will do this for 3 or 4 cycles before it finally runs and accelerates normal.

[KingSlew]

You might have to boil it out to loosen the varnish.

Use about a cup of WHITE vinegar to a couple of quarts of clean water, enough water to cover the parts.

Strip the carb down, being careful to remove the rubber parts and gaskets. Do NOT soak the rubber parts or gaskets, set them aside.

Bring the mix to a soft rolling boil. Maintain this rolling boil for about 45 minutes or so, adding water if necessary to keep the parts covered.

Drain and replace with clean water. Bring the water back to a soft rolling boil for another 30 minutes or so to rinse the parts.

You'll find the parts will be covered with a soft white powder... this is normal and it will brush off.

Blow it out with compressed air. Boiling is the best way to clean a carb.

[Hoghunter]

Well this is becoming a true PITA. I have now had the carb completely apart twice and I'm still having problems. I will admit the problem has improved but it's still not normal. The fact that I have had improvement in how it runs tells me I must be on the right track but I don't know why it's so dang difficult to get the carb to operate correctly.

I pulled all the jets etc out of it yesterday and soaked the carb bowl and all parts removed in cleaner. I then blew out all the passages with my air compressor.

It improved the performance but as stated above it's still not normal. I talked with the Yamaha shop today and they told me that sometimes they have to take these carbs apart two to three times and clean them before it works.

I haven't done the flywheel removal as I got to believe it's fuel since it does eventually go away once you run it long enough. I haven't done a carb rebuild and maybe that is the next step.

This ethanol is a real PITA.

[gerberman]

We had our yami in the shop for fuel, problems??? carb problems??? jet problems?? and it was the broken key. It might be worth the time to pull the flywheel just to make sure. You cannot tell looking from the top. Your problem sounds just like ours. We spent all the time doing all that you have done.

[Hoghunter]

Originally Posted by gerberman

We had our yami in the shop for fuel, problems??? carb problems??? jet problems?? and it was the broken key. It might be worth the time to pull the flywheel just to make sure. You cannot tell looking from the top. Your problem sounds just like ours. We spent all the time doing all that you have done.

GB, I plan to break out my compressor and air gun this pm and check on the woodruff key. Do you have to actually pull the flywheel to see if the key is broken or can you tell by removing the magnetic nut?

[tomictime]

Jeff: you are welcome to swap my t8 carb in and see if it cures the problem....

[Hoghunter]

Originally Posted by tomictime

Jeff: you are welcome to swap my t8 carb in and see if it cures the problem....

Jim, thanks for the offer. We'll see how my latest round turned out when I test her again tonight. May take you up on it.

[gerberman]

You have to pull the flywheel, I found 2 pieces of key, put in a new one and it works great. Gerberman

[smalldog]

Originally Posted by Hoghunter

GB, I plan to break out my compressor and air gun this pm and check on the woodruff key. Do you have to actually pull the flywheel to see if the key is broken or can you tell by removing the magnetic nut?

The key is to align the flywheel it isnt supposed to hold it in place. the tapper does that when the nut is tightened.
Very rare to have that happen...worth checking though.
I use a sonic cleaner and it does very well getting the tiny passages clean it uses heat/ cleaning solution and a vibratory action.

To pull it..use the air gun to get the nut off and a flywheel puller. Remember the bolt holes are metric and dont run them in.. use your hand and just put them in to get 1/2" of thread in the flywheel. The coils underneath can be damaged if you run the bolts into them.
Also..if you can...use a flat cup over the end of the puller rather than to use the tappered end that goes into the machined dimple they use to machine the crank. Reason is that the pressure in the tapper can split the end of the crank...then your in real trouble.