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Honda 20hp clean carb but will not idle

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pts99827

New member
Hello, So this is my 2nd post, I'm just wondering what I should be checking if my 20HP outboard is not running properly. The motor has been run in salt water and flushed once in a while. The thermostat and the area around it was heavy with salt, but when I opened the carburetor, it looks basically brand new, other than the gaskets which I replaced. So is there another reason the motor will not idle properly and/or will not stay running, even if the carb is super clean?

Thanks for any input.
 
Firstly,flushing once in a while is asking for headaches. The small Hondas get major salt deposits building up the the bottom of the water jacket that the thermostat is located in as well as small passages in the cylinder head, these issues will lead to overheating . As far as your idle issue is concerned, looking at the bowl is not enough, the idle jet located in the tube that goes up through the venturie is very small and can be blocked even when the rest of the carburetor looks clean. It would be a big help to you to use a manual to identify the jets and go from there.
 
Hi,

Sorry you're having problems.

I agree with eneuiis that a carb that looks clean doesn't mean it's not plugged in some way. As he stated, the only way to KNOW if all is clear is to test each passageway for flow using a spray cleaner. These little carbs are just plain hard to get properly cleaned up without some specific knowledge of the way they work.

I always recommend buying the HONDA MARINE CARBURETION MANUAL if you want to DIY it. It's much cheaper in the long run than taking it to someone that may not know much more about them than you.

Question though: does your outboard have a black, rubber cylinder attached to the engine oil dipstick tube? If yes then you may want to try taking it off and shaking all the liquid out then putting it back and try running the engine. That "device" is called a "fuel chamber". It should only have gasoline in it but it can act as a water separator and fill with a goodly amount of H2O. When it does, it causes running problems.

Good luck.
 
Hi,
Just my opinion since I've never seen that happen before but, yes, a crack in the intake would effect engine vacuum so it might cause all sorts of "symptoms". Including hard starting.

As far as welding it goes, I think it could probably be done. That is, depending on where the crack is in the "runner" and the skill level of the welder.

This will likely require a professional using Tungsten Inert Gas (TIG) process.
It might also require removal of the cylinder head to gain complete access.

Sorry this happened to your outboard.

Good luck.
 
jgmo said:
Hi,
Just my opinion since I've never seen that happen before but, yes, a crack in the intake would effect engine vacuum so it might cause all sorts of "symptoms". Including hard starting.

As far as welding it goes, I think it could probably be done. That is, depending on where the crack is in the "runner" and the skill level of the welder.

This will likely require a professional using Tungsten Inert Gas (TIG) process.
It might also require removal of the cylinder head to gain complete access.

Sorry this happened to your outboard.

Good luck.
Click to expand...
Many thanks
 
Yes, I've seen this twice, in both cases I replaced the cylinder head, both times under warranty, so it does happen
 
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