9.8 Tohatsu dies out after initial start

[TCulver]

I have a 2015 9.8hp Tohatsu outboard that I recently dismantled and cleaned the carburetor, and it was running fine for the past two weeks. Now it starts but after the initial start, 20 to 30 secs of normal operation, it starts to struggle and then dies and cannot be restarted. Seems flooded. There is a smell of gas. The sparkplugs are NGK and new this season. A friend told me that the carb jets might need to be adjusted (??). Instead of going through that process, if thats even true, I figured was easier for me to replace the carb with a new carb. I did so and started the engine with the new carb. It fired right up, but again after about 20-30 secs it dies out. Any ideas on what might be causing this? Next step to investigate? Thanks in advance for any advice.

 

[pvanv]

The jets are not adjustable. I would check that you are getting good fuel delivery. A leaky o-ring in the fuel line could cause that symptom.

 

[TCulver]

Thanks for the suggestion! I’ll check it out!

 

[ThomW]

Is it a remote tank? Could be as simple as forgetting to open the vent on the fuel tank and causing an air lock after a running for a few seconds....

 

[MattFL]

I'm with these guys, sounds like a fuel delivery problem. If there's a squeeze ball in the gas line, squeeze it and see if that temporarily resolves it. You can also open the drain screw on the carburetor bowl and check if it's full of fuel.

 

[TCulver]

Is it a remote tank? Could be as simple as forgetting to open the vent on the fuel tank and causing an air lock after a running for a few seconds....

Yes it’s a remote tank. I’ve opened the vent still running into the same issue. Thanks for your suggestion tho.

 

[MattFL]

Yes it’s a remote tank. I’ve opened the vent still running into the same issue. Thanks for your suggestion tho.

Does squeezing the ball resolve it?

 

[TCulver]

I’ll try squeezing the ball and will check the bowl. To me it seems like too much fuel due to the smell of gas and not being able to restart it afterwards. Reacts like it’s flooded. Is it possible too much fuel flowing into the carb?

 

[MattFL]

It's possible if the float was sticking or the float valve had some debris stuck in it, but you put a new carburetor on it so that makes a float issue unlikely. If you think it's flooded, remove a spark plug and check if it's wet with gas.

 

[ThomW]

I agree that while it sounds like a stuck float...2 carbs makes that unlikely. Also check the fuel line and connections for any cracks or non secure fits. Could also be sucking in air somewhere along the fuel delivery causing it to stall out.

 

[TCulver]

Great advice. I’ll take a look!

 

[MattFL]

I'll bet you've got a leak in a fuel line under the hood somewhere and what you're smelling is gas that leaked out, and when the motor is running air is leaking in.

 

[TCulver]

Thanks for that! I don’t detect any leaks, but will replace fuel lines and fuel filter.