Poor idle on '97 Honda 15hp

[DewDropper89]

Hey all. I have a 15 horsepower 4-stroke Honda that I've owned since 2004. It has always been a little finicky about idling way down, but the problem seemed to come and go. Now it seems to be the norm instead of the exception and has gotten to the point where you need to throw it into gear at higher throttle than feels good and then get on the throttle right away once in gear to keep it running. It is extremely frustrating, especially in current or heavy wind. I have always winterized it by running fuel with Sta-bil through it and then letting it run out of fuel; I fog the cylinders as well. I generally put Sta-bil in the gas as well because I use the boat/motor relatively infrequently. I have changed the plugs and shot carb cleaner down the intake before with no luck - any other ideas? Fuel filter? Anyone had bad luck with Sta-bil? Anyone had similar problem with same motor? Should I dig into the carb? I am close to bringing it in, but would like to make one more run at it. Thanks for your thoughts.

[boatfixer]

It really sounds like the carb needs to be rebuilt. I'm willing to bet there is some crud in the idle circuit somewhere. Spraying carb cleaner through the throat will not clean anything inside the carburator. Relatively easy job if you have any mechanical skills.

[DewDropper89]

Do you think it needs re-building or maybe just to be torn down and thoroughly cleaned? It is a job I'd take on either way, I am a decent weekend mechanic if I put my mind to something and as long as I have time. Any special tools I would need for this?

[boatfixer]

taken down and cleaned, but as long as your are doing it, why not put in a kit? new needle and seat etc.

[jjz]

Had a 15 and currently run a 20. I would agree with rebuilding the carb. Also on both my Hondas I have gotten a far superior idle with premium gas 91 octane +, allows a smoother idle at lower rpm than 87 octane.

[Ryoushi]

I have a 15 and I tore it down and both jets were almost completely plugged. Now this was just from letting it sit for about 3 weeks in the hot weather. There was also varnish in the bottom of the bowl. I put it back together and used all my old gaskets and it has been running like a champ since. I was too cheap to pay 50.00 for a couple of gaskets and a needle.

[BoxMN]

I have same problem with my '96 Evinrude 25hp (I posted as well). Consensus was carb clean/rebuild, and am going to do that.

[DewDropper89]

Thanks for all the good advice, all. I decided to tear it down and just give it a thorough cleaning - runs like a champ now, only took maybe a little over an hour start to finish. Actually did not note any real obvious gunk or gumming inside, but blasted pretty furiously at the main jet and the idle circuit until everything was obviously flowing nicely. A dealer who services Hondas said that Honda doesn't sell rebuild kits, so I just cleaned and put it back together. If I end up having to do it again for any reason down the road, will maybe look into the rebuild at that time. Thanks again.

[boatfixer]

Glad to hear you are back on the water DD89. All you would really need would be any neccesary gaskets, needle/seat, and float. You wouldn't need to replace throttle shaft and that kinda stuff.