2006 Honda 9.9 Stalls in Gear in Idle

[ahicks]

My plan generally involves compressed air and carb cleaner as well. Every passage is checked. Carb cleaner is forced through it, then compressed air.

And I've had carbs apart 3 and 4 times as well. Patience required here. This story "I've already cleaned the carb" carries very little water if the problem persists. Clearly, they missed a section somewhere....

 

[MattFL]

My plan generally involves compressed air and carb cleaner as well. Every passage is checked. Carb cleaner is forced through it, then compressed air.

I've always done the same, but adding the heated ultrasonic really stepped it up to the next level. They're cheap now, some are under $100 on Amazon, definitely worth a shot if you find yourself cleaning anything often that would fit inside one. I toss everything in there that will fit; carburetors, nuts and bolts, anything mechanical that's greasy that needs to be clean. They even work fantastic on old fishing reels. My son started going through a pile of old antique reels he inherited that had grease that must have been from the 50's dried up inside them. After some soaking they came out shiny and clean. Reassemble with new grease and many of them work like new!

 

[DaBears]

Thanks folks. While it is working great presently, assuming it stays that way I plan to use it this way this season. Over the winter I will do a long carb soak/cleaning and change the impeller for next season. Caught a 27 inch landlocked salmon yesterday so not interested in fixing/investigating further unless I have too.

 

[HJD]

New to this forum but having a stalling issue on a 2006 Honda 9.9. The 14 foot fishing boat and motor are new to me. There was a similar thread a number of years ago but never really got a final resolution.
I changed out the impeller, plugs, carb cleaned, changed gear oil and engine oil, and a new prop. Works great under throttle. When not in gear it will idle all day long. When in gear and going to troll after the engine has been throttled up it will idle for around 2 minutes then shutoff with no warnimg. Starts up right away and runs 1 min 17 seconds then shut off without warning. Starts right up and will idle in gear for 1 min 17 sec then shuts off. Repeats the same. No apparent leaks in the fuel system and I changed the fuel out with fresh and Seafoam and got rid of the old fuel. Certainly not ideal for trolling. E-Start and automatic choke. Overall engine works great except this 1 min 17 sec stall issue in gear in idle. Has me thinking that maybe the prop pitch is slowing the RPM too much???? I believe it is a 9 or 10 pitch. Certainly when it is in gear the RPM decreases a bunch as compared to out of gear but it doesn't sound like it is labouring. Trolls too fast anyway so have ordered a 7 pitch prop for it which will also increase the RPM and slow the troll speed. Any thoughts or comments? I would love to sort this out so I can reliably use the motor without wearing out the E-Start. Thanks.

On a lot of carbs, there are tiny holes in the throat just past the throttle plate.
These holes are part of the idle circuit. I usually use the smallest welding tip cleaner to make sure those holes are open. Just poke them clean, don’t file them larger. They are so small you may need a magnifying glass to see them. Their function is to feed a small amount of fuel to the engine even though the throttle plate is closed. The rest of the idle fuel is measured with the idle/mixture screw. If those holes are plugged, your engine is starving for a portion of it’s idle fuel. A lot of times cleaners , ultrasonic, and comp air don’t clean these tiny holes. This also cures a lot of surging problems on all your small yard engines.

 

[DaBears]

An update on this issue. I cleaned the carb again but the issue remained. Took the carb to a guy with an ultrasonic bath and he cleaned it but the issue remained. Unhooked the temperature sensor and the issue disappeared. I bought and installed a new sensor but the issue is the same. The telltale flow seems good to me and not hot but regardless I am going to put in a new impeller (a new one was installed in early May but......) once it arrives and see how it goes. If that doesn't work I am thinking to run it in some vinegar and a little dish soap and let that soak in it for a bit to see if that does anything.

 

[MattFL]

The problem disappearing after unhooking the temperature sensor is a big hint. Figure out what is controlled by the temperature sensor (is it the choke or enrichment circuit?), maybe something else in that pipeline is bad.

 

[starcraftkid]

I had a slightly older Honda 9.9 a few years ago that would run about a minute and half then shut off. I'd pull the cover, tinker with the carb and it would fire up again. The idle was low, and a bit unstable. It took me a while to realize it only ran bad with the cover on it. If I pulled the cover, it ran fine.
What it turned out to be was a crack in the exhaust tube that was letting exhaust leak up into the engine area choking out the motor.
The first couple times it happened I would have sworn it lost spark or got turned off somehow.
A compression check is also important on those, I've run across quite a few later Honda motors with pretty low compression, whether it was a worn motor or a valve adjustment issue I can't say as I just walked away not wanting to gamble on it.