Yamaha 9.9 problems starting and with staying running

[genEus]

All right guys, you're my last hope before I go to the dealer... Here's a bit of background... Going to try to give a lot of info up front.

I bought this motor a couple months ago. It's a 2006. I put it on the water and ran it about once a week on a 16 boat, trolling with it for about 3-4 hours every time on idle. I'd go WOT for maybe 5 minutes and then drop down to idle and troll. The only issue I have ever experienced was if I dropped the RPMs very abruptly, the engine would sputter and die, but when restarted it would keep running. In idle it was also never totally "smooth" as it turns out but I didn't know any better, it seemed fine to me.

Last week I took it out on the lake, it started up fine, idled for a few minutes, then as I started taking off, it died, and wouldn't start back up.

Here is the progression since then:

PART I

I took out and cleaned out the carb (as best as I knew how, I may have certainly missed something, who knows), using a strand of wire to go through the nozzles. The body looked clean, with no deposits. I cleaned up the spark plug contacts - they were sooty. I cleaned the fuel filter, I cleaned the fuel pump. I put it all back together and the motor started purring like a kitten. Started up and stayed running (in my driveway in a trash can with water). No hiccups, nothing. I took it for a short test ride on the canal and it worked better than it did when I bought it. It started right up and stayed running. I warmed it up, then put it into gear and at idle went for about a half a mile. It was smooth as silk, like never before. I was celebrating my victory. Then I opened up the throttle some, then some more, then went to WOT. Went on WOT for about 30 seconds, before it started slowing down, then choking up, then it died. After that, all the original symptoms came back. Wouldn't start up; with the choke started up, revved up high, then sputtered and died.

PART II

Last night, I replaced the plugs, cleaned out the carb again, blew through the fuel pump again. Then got to thinking that it can't be the fuel delivery system bc I primed the bulb and heard the carb fill up. At that point, it should have started, regardless of the fuel pump or filter even being in place. So, at this point I'm down to the carburetor being bad (I inspected the float for cracks or whatever, and couldn't see anything, but as I said above, there might be things I missed otherwise), or the electrical.

Need your guys' help! Does anyone have any suggestions??

Thank you!

[Mosh]

Check your fuel.

Pour the fuel out into a large glass jar (I use a pickle crock) if possible and look for water or cloudy gas/oil pockets. Or just dump the whole can and get fresh fuel, but make sure to wipe out the crap in your tank if its in there.

I had the same thing happen to a 7.5HP merc. It was all in the gas.

The only other things I have encountered is vaporlock in the fuel delivery system which takes a while to build up while running or no vacuum at all. Make sure the gas tank is vented. Make sure there are no holes in the tubing or dry rot on the ball.

It sounds like your motor is fine and will work if given the right fuel.

good luck!

[skipper19]

4 stroke?..definitely fuel delivery problem if needing choke. Start at the float valve. Remove it. Take the needle out. Clean the seat of any debris. Rubber pieces get lodged there from the hose...ethanol trouble. Needle and seat are narrow passageway and easy to clog not allowing enough gas in the bowl. Opposit can happen too. Needle won't seat and gas floods the bowl. Be sure next to check o rings on the hose connectors, no cracks, none missing. Clamps are there and tight on bulb. Check valve in bulb working....just to start with.

Mark

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[genEus]

Skipper-

Yes, 4 stroke. I took out the bulb and the needle valve 3 times now, cleaned the seat, the valve, everything. To be honest, the internals of this motor are like brand new. So far I have not seen a single speck of dirt in anything that I had cleaned. The funny thing to me is really that I got the motor to work LIKE it was brand new, except now it doesn't. So, something I touched definitely hit the spot. I just have no idea what it was, bc none of this makes sense.

I would go with the fuel delivery theory but the engine won't even start now. when I prime the bulb I can see fuel being sucked into the fuel filter, and then I can hear the fuel filling up the carb. at this point, when the motor actually did run, it would start and could idle for 5 minutes just on the fuel in the carb. but now it wont start no matter what...

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[hermit]

I'm with Mosh, and it's easy to check/change and could work wonders. My Stihl wouldn't start once no matter what I did. Gas looked fine, no water in the bottom, but I put in new gas and it ran like a champ. Another time the lawn mower wouldn't go after sitting a bit, turns out the tank was rusting and the gas was red. If that doesn't solve it at least you know.

P.S. Also once when playing with the carb on my outboard I put the float in upside down... definitely didn't work then!

[genEus]

I'm with Mosh, and it's easy to check/change and could work wonders. My Stihl wouldn't start once no matter what I did. Gas looked fine, no water in the bottom, but I put in new gas and it ran like a champ. Another time the lawn mower wouldn't go after sitting a bit, turns out the tank was rusting and the gas was red. If that doesn't solve it at least you know.

I'm gonna try that tonight. It just amazes me that it would stop working *all of a sudden* like this if it's a fuel quality problem, but sure I will try.

One thing I noticed is that the connection between the fuel tank hose and the connector on the motor is leaking. If I pump the bulb too hard, I start seeing fuel leaking out of the connection. Also, when I prime the bulb and the fuel is sucked into the filter/carb, I can hear air being sucked in through the connector. Could introduction of air in there cause a problem?? I can try to temporarily wrap duct tape around it... to prevent any air leakage.

On the topic of the bulb - in mine there's no way to put it in wrong because of its shape. the lid won't close

[skipper19]

Sucking air is where I was suggestions on o ring damage. You are losing prime. Bet that is it.

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[ray koziatek]

It really sounds like water , I got some in my small tank once ,almost would run then die pull 1000 times and mess with choke kinda fired putt a little bit then nuttin was very small amount of water as i did get it going sputtering away till all water passed...dont forget to drain the fuel line before ya test out new fuel.

[genEus]

well, I followed everyone's advice, dumped the old gas, filled with fresh gas, added marine stabil, cleared all the fuel lines, and dumped the fuel filter. I do believe I saw water in the fuel filter. I didn't know what the water would look like, but there was clear separation there of 2 liquids. although, I can't say that I saw water in the main tank fuel, but perhaps it's because it got mixed as I was pouring it out into a bucket?

anyways, it took about 10-15 pulls, but the motor started up, and ran just fine. it now still does that thing that I thought it stopped, if I rev it up and then quickly down, it stalls. but it restarts just fine after that.

crossing my fingers and my toes. didn't have time to drop it in water today, but will post results when I do! seems quite promising. But I am not celebrating just yet.

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[Gill-T]

Make sure your spark plug is the recomended brand. I tried on my 9.9 merc to replace the standard NSK with a Champion plug and had a horrible time getting a spark. Put a new NSK in and voila problem solved.

[jimski2]

West marine Chinese hose fittings are junk

Changed 6 of them. Go to a real oh dealer for hose fittings.

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[genEus]

To the last couple posts: new spark plugs are NGK, just as the old ones were, and that's the recommended brand in the user manual.

Which hose fittings? I am concerned with the male fuel connector on the motor itself. There's definitely a small leak between the female fuel line connector and the male connector on the motor itself. Whether that creates a problem or not I don't know... But the hose fittings on the fuel hose are Moeller and they're brand new as are the fuel lines, bulb, and the tank.

[genEus]

A new discovery.

I noticed that I can easily overprime the carb and fuel starts shooting out from the top when I do. I thought this would be normal, but from reading online I've learned that when the carb fills up and the float rises, the needle valve is supposed to shut off the fuel completely and you shouldn't be able to pump more fuel in the carb. However, mine seems to take it. The bulb feels pretty hard, but not so hard that I can't keep pressing it, and when I do, fuel spews out the top of the carb.

Thoughts?

[buckboardjr]

Sucking air is where I was suggestions on o ring damage. You are losing prime. Bet that is it.

Skipper19 allready sent you down the path of your leaking male connection. Definately fix your leak

[genEus]

Sucking air is where I was suggestions on o ring damage. You are losing prime. Bet that is it.

Skipper19 allready sent you down the path of your leaking male connection. Definately fix your leak

Yeah I'm definitely replacing the fuel connectors or the o-ring(s) around them.

Also, when I press on the bulb, fuel spews out of the connector even if it's not plugged into the motor. Is that bad?

[jimski2]

That is it. Female connector o rings leaking. Suck air. Leak gasoline

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[Mosh]

I would ignore the gas overflow into the carb for now and replace the tank to motor hose. If there is a leak anywhere in this connection you will lose prime (or vacuum as I said before) and the motor will stall out.

Sounds like the connection at the motor is the prime suspect and I've seen the female connection go bad more than the male. A new hose will probably do you wonders.

You also had more than one thing going on. When you get water in your gas its like italian dressing, they don't mix and separate. Unless shaken with oil, then it turns into an emulsion of oil-gas-water...very similar to the cruet in my fridge! \

I use olive oil in my dressing though!

[genEus]

I would ignore the gas overflow into the carb for now and replace the tank to motor hose. If there is a leak anywhere in this connection you will lose prime (or vacuum as I said before) and the motor will stall out.

Sounds like the connection at the motor is the prime suspect and I've seen the female connection go bad more than the male. A new hose will probably do you wonders.

You also had more than one thing going on. When you get water in your gas its like italian dressing, they don't mix and separate. Unless shaken with oil, then it turns into an emulsion of oil-gas-water...very similar to the cruet in my fridge! \

I use olive oil in my dressing though!

somehow, I was thinking just that. I was going to ignore the overflowing carb for now, and replace the female hose connector. the o ring is all torn up! I'm sure I can find it at gander mtn.

the overflowing carb, however, has me concerned as well. it's hard for me to picture how any of the 3 components that a child could put together would have anything wrong with them to make the float stick, or the needle valve not close. I have taken it apart and put it back together 3 times now, and I just don't see it.

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[ray koziatek]

pieces of hose stuck in needle valve ??

[genEus]

pieces of hose stuck in needle valve ??

somehow bypassing two 10 micron fuel filters? (the carb fuel intake also has a mesh)

not to mention 3 cleanings with carb cleaner, compressed air, and a piece of wire in all the openings?

gah. it's been a heck of a week trying to figure this out.

[jimski2]

Get. Your. Hose. Fitting. From a dealer. Not from an outlet.

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[genEus]

Get. Your. Hose. Fitting. From a dealer. Not from an outlet.

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" thanks" for the advice

my conversation at the yamaha dealer 2 minutes ago...

he: " that will be $25.49". I: "sheesh." he: " it's a boat, brother!"

this connector really does look very different from the moeller... we'll see.

also I talked to one of the yamaha mechanics and he said that if you gently press on the bulb, until it is firm, and then don't press anymore, the needle valve should hold the fuel in the carb. but he did say that if you squeeze the bulb after that, the fuel will raise the needle valve and start shooting out at the top of the carb...

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[genEus]

Well I think I got it! Took it out for a long test drive and it worked flawlessly. WOT, idle, quick RPM changes up and down, no flooding, no sputtering, no stalling.

Hopefully this helps someone in the future. To summarize, here are the things I did:

- Cleaned carburetor, fuel filter, fuel pump

- Replaced gas in tank with fresh gas; added Marine Sta-Bil; blew out all the lines

- Replaced leaky aftermarket (Moeller) fuel hose connector with a Yamaha part <<-- big difference! When detached from the motor, fuel doesn't come out of hose when I press the bulb like it used to, fuel doesn't leak out at the connection to the motor and air doesn't get sucked in.

(Got a fuel/water separator that will install ASAP as well).

I could not have done this without you guys! I'll update after the next time I go out fishing, but looks promising!

[Mosh]

Hopefully you got out this weekend! I was stuck running an excavator and installing drain tile...what a fiasco.

[jimski2]

6 chinese fittings cost more.

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