9.9 Honda - Poor idle and stumbles

jimi

Petty Officer 2nd Class
Joined
Jul 28, 2003
Messages
147
My 20 year old Honda 9.9 is idling very poorly. To get it idling it works best if I apply 10 or 20% choke which makes me think that the low speed jet is gummed up.

I have to keep rev'ing it up in order to move into gear. And It stumbles when I rev it more so in gear that when in neutral.

I change the gas completely and if anything it seems to be getting worse.

What should I check out?
 

Sea Rider

Supreme Mariner
Joined
Sep 20, 2008
Messages
12,345
Seems you need a good carb cleaning, that's soaking for some hours in carb cleaner dip, remove all plastic bits previous doing so, clean internal gas tank & fuel pickup mesh internal filter, fuel line, large mesh fiilter inside engine too. Change spark plugs too, engine should work much better...

Happy Boating
 

jimi

Petty Officer 2nd Class
Joined
Jul 28, 2003
Messages
147
I took off the carb and gave it a quick clean. I reset the low speed mixture and idle speed. Seem to help a lot. It idles, which is far better, but it is still a bit rougher than I remember. I'm going to get a new gas tank (the old one is 20 years old, sun bleached and leaks) and fill it with new gas next.
 

isaksp00

Petty Officer 1st Class
Joined
Jul 14, 2010
Messages
225
On my 8HP Honda I always make sure I thoroughly clean the idle jet that can be removed from the top of the carb.
 

jimi

Petty Officer 2nd Class
Joined
Jul 28, 2003
Messages
147
Yup, I had the needle out during my quick cleaning. I also took out the high speed jet and gave in a good solvent and tooth brush scrub.

While I was cleaning the carb I notice some rusty, vanish like substance right in the bottom of the bowel. I scrubbed it with the solvent and a tooth brush but it still persisted. It isn't in the way of fuel flow so I'm not worried, but it is interesting how hard it is to remove residue once it's stuck on in a carb.
 

isaksp00

Petty Officer 1st Class
Joined
Jul 14, 2010
Messages
225
I'd also do what SeaRider recommends and clean the whole carb thoroughly by soaking. Despite my doing that, my idle jet tends to clog a few times a season even though I disconnect the fuel line and run the carb dry every time. At least it is easy to remove. I find that the plastic floss threaders you can get in the dental section of a drug store, and carb spray, work well to help clean the tiny center hole, when you can't dip it. You can do that on the water.
 
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