Outboard stalls

[gettinthere]

My Tohatsu 9.8B 2 Stroke outboard starts OK but slowly looses idle speed and stalls. I adjusted mix screw with no good result. Checked plugs...wet. Gap good.

So I have a flooding problem. I'm in the Bahamas and neglected to buy a shop manual.
Suggestions on what to look for and how to deal with it?

thnx

 

[Bill Roosa]

If it starts and then stalls due to too much gas (not sure if that is the case) that would tell me that the carb/fuel system is having issues
Can you restart it after it stalls?

 

[gettinthere]

no, the plugs are wet. If I dry them and wait a few hours, it would start again.
this slowly got worse over a few weeks...shoulda jumped on it when it first appeared!

 

[anchorclanker]

If its flooding, the most likely cause, often the only cause, is a bad needle and seat on the float, in the fuel bowl. Sadly, the only cure is a new needle and seat. They are generally quite cheap (though maybe not where you are), but you have to find one.

You generally have to remove the carb to remove the fuel bowl, though on some motors you can drop the bowl in situ. Not familiar with the Tohat. The float is removed, usually slide a pin out, and the needle and the seat should be self explanatory. You should be able to find exploded views online to aid you.

OTOH, how far did you adjust the mixture? Did you choke it? My Crystal ball doesnt work so well, but quite often people over choke a hard starting engine, due to a weak fuel pump/fuel starving, and inadvertently flood the darn thing. Then you believe its flooding, when in fact its not.

However. Often times, if the needle and seat have died, the fuel pump parts are next, if they arent failing already. As long as your doing the carb, replace the pump parts too. May also want to look at the fuel line and squeeze bulb.

 

[caguy]

My Tohatsu was doing the same thing. It turned out to be a loose fuel line clamp. I was sucking air and not enough gas.

 

[gettinthere]

"over choke it"? The pull choke works fine, helps cold starting. I push it in right after starting.

I've tried to fix the problem with the needle valve at various settings and always get the flooded plugs.

This started about 2 weeks ago after running a long time. Now it stalls after a short period of only a few minutes. It progressed very fast.

caguy...how would not enough gas lead to fouled plugs?

I do see some evidence of gas under the carb. Very difficult to determine where it came from.

 

[kloudie1]

If that engine has a float bowl vent line , bugs in this line will cause what you are seeing. Look for a small rubber tube that connects to the top of the float bowl housing and exits under the housing. If a spider or mud dauber plugs the tube end, it results in an air lock that keeps the float from shutting off.. same symptoms as Anchor describes.... Unplug the tube and it starts working again..
I don't know that engine but it is a possible to look for. I have had that trouble on my old Honda and an old Johnson..

 

[Rick]

Sounds like the jet is clogged to me. My Tohat gets that way with similar symptoms. This wont cost you anything but a bit of your time. Remove cover and find the carb. Remove the float bowl. Inside you will find a single jet that will unscrew. Clean the gunk that is probably in it out and replace. Hopefully that will cure your problem. Recommend having the motor on the hard when you do so no parts go to Davey's Locker.

Cheers

 

[shemandr]

My Tohatsu was doing the same thing. It turned out to be a loose fuel line clamp. I was sucking air and not enough gas.

I got rid of that clamp, and put in an in line filter. I used hose clamps. Much better performance. It went from being the engine from hell to a trusted friend.

 

[caguy]

You described the motor stalling after idling for a while. Does it stay running if reved up or higher idle. I also increased the idle speed to prevent stalling, it doesn't take much.
Plugged idle jets will also cause those symptoms.
When you squeeze the bulb hard does gas drip out the carburetor vent hose? If so it may still be your float and or valve.
I think what he means by over choking is continued pulling of the starter cord with the choke out.

 

[anchorclanker]

Sorry, plugged jets don't cause flooding guys, plugged jets just mean it starves for fuel and quits/wont run.

Claude's suggestion of a plugged fuel bowl vent is plausible, and would also lead to fuel drips, as you noted. Outboards dont have air filters, some dont even have screens. Most carbs vent to the air intake where most other engines have a filter. Its not out of the question for a bug to plug it up.

Loose fuel line and sucking air would also not cause flooding. Fuel starvation yes, flooding no.

Only a two things will cause flooding of a carbureted motor. Over choking, or the fuel bowl physically overfilling. And only a few things will cause overfilling; a damaged needle/seat, a plugged bowl vent, or excessive fuel pressure.

Another good reason to remove the fuel line from the motor, and run it out fuel after use; The fuel system can pressurize if left in the sun/heat, if you close the tank vent. That constant pressure on the needle and seat will shorten its life. Not all tanks have vents but many of the older ones do/did.

 

[sailaway78]

Another thought

I recently went nuts trying to keep the outboard running on my little skiff. Was doing pretty much what you have described. Would start and run for a few seconds, the die. Had water in the gas. Soon as that was cleared out, it ran fine.

 

[Bill Roosa]

Youall do know that there is an idle circuit and a power circuit right?
The power circuit works for all throttle setting that are not idle. that other important looking screw that is not the idle speed screw is the one. smartly called the idle mixture screw.
Soooo
Does the unit run ok but just not idle? or does it die no matter what you do?

 

[gettinthere]

well, I bit the bullet and pulled the carb. Concerned about doing this since we're in the Bahamas away from easy sources of parts.

The fuel lines were wet so I replaced the clips with real clamps.
The float did not sit level when held upside down so I bent it a bit to level it.
I've had the needle out several times and it was clean but I pulled it again and it was still clean. Blew compressed air into the seat. Other than that, not much I could do without a rebuild kit.

I did not find a vent tube on this carb. Might have been internal within the casting?

It started up fine and seems to run OK. Left it idle quite a while with no stall. I'll take it out for a longer run tomorrow when wind is light and water calm.

 

[Rob2435]

If it's a four stroke, the carbs tend to have problems due to the tight tolerances and the use of ethanol. When ever my outboard acts funny, I pull the carb and spray it down with carb cleaner, it has worked every time.

 

[anchorclanker]

If the float was high it could have very well been your problem. If its too high it could touch the casting and the needle wont close. It is extremely unusual that it would bend on its own. If the problem has been getting progressively worse, and bending the float back fixed it, I would be very concerned the float may be suffering from metal fatigue and the problem may return, but next time there may be no way to fix it if it actually breaks. You might consider ordering a replacement if you suspect that is the case. The only other way for it to bend would be someone physically bending it, or some extreme force, dropping the motor hard for example, or continuous bouncing on the back of a boat.

The vent is more than likely routed to the outside of the carb at the air intake, just off to the side you may see a small hole.

 

[Granfalloon]

Simple stuff.
- Check for bad gas - Siphon some from the bottom of the tank into a clear container/soda battle. See if water settles out on the bottom.
- I use Ethanol Shield (additive) to my fuel.
- I use "Mechanic in a Bottle" (additive) to clean the Carb/Jets
- I disconnect the fuel line and run the engine to flameout.