2006 Honda 9.9 Stalls in Gear in Idle

[DaBears]

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.

 

[Sea Rider]

To play with prop pitches the pro way need to count with a tach, with motor 100% healthy go for a wot run as loaded on flat calm open water and check the achieved wot rpm, from there can go straight for a prop maximization to less prop pitches once knowing that. It's extremely dangerous installing a 7 pitch blindly, can over rev the motor and won't know a thing about that scenario..

Happy Boating​

 

[racerone]

Nothing to do with prop pitch I think.----I say there is an issue in the carburetor.----Idle passage ways are very small , like tiny.----Clean the carburetor again.

 

[MattFL]

The manual will have a spec for the idle speed. Check your in-gear idle speed against the spec and make sure it's not too slow (use a tachometer, don't guess). But also as mentioned above, small 4-stroke carburetors have tiny little passages that are notorious for clogging up and affecting the idle, so giving the carburetor a good cleaning could help as well. Shoot cleaner through every hole followed by compressed air, focus on the small idle circuits. A third thing, unstable idle can be a sign of the valves starting to tighten up, so it wouldn't hurt to check the valve clearances too.

Side note; I've got a 99' Honda 50HP, and as the hours added up it started having idle problems too, that were not corrected by any of the above. The idle would either be much too high or it would stall easily, there was no middle ground. What fixed it was removing the EPA limited fuel screws and installing normal fully adjustable ones so I could adjust the air/fuel ratio at idle properly. Now it idles very stable. I'm sure your 2006 probably has something similar, the fuel screw that can only be turned about 1/8 of a turn. If the above doesn't fix your idle problems, see if you can find the part number for the non-EPA fuel screw. You might be able to use the fuel screw for the same motor, but the non-USA model. To get the old one out, a soft tap with a hammer will break the head right off, then use a left hand drill bit or screw extractor and it will come right out. Then thread the new one in like normal and you're good.

 

[DaBears]

Thanks for the input. Also should of said that the idle tube in the carb was replaced (the one with the many extremely tiny holes). The previous one had a small split in the tube (fish mouth split which makes me think it had water in it and froze and split). The choke also didn't work as that passageway was fouled but all good now. Pumping the primer bulb has no effect. I guess my concern here is way 1 min and 17 sec which is exactly the same time two other posters had. To me it sounds like there is something shutting the motor down at an exact time. I suspect at the low idle RMP that maybe there isn't enough cooling or maybe the fuel pump doesn't work right (the telltale certainly isn't hot the lake is only 50 F right now and the primer bulb has no impact).
I don't know the RPM numbers. It isn't even close to WOT RPM now in gear as compared to reving it out of gear. At idle it currently has good RPM out of gear but it clearly decreases a bunch when in gear. I am going to try today adjusting the idle screw up (when in gear) to a RPM that sounds right to me and see what happens with it shutting down. I know I won't want to leave it that way as I don't like the idea of clunking the motor in gear at the higher idle RPM that this exercise is going to result in. I will report back and see if you folks have any additional comments.

 

[MattFL]

You can get a combo hour meter & tachometer on Amazon for around $20. Not super precise, but good enough to help you set the idle to spec. It's a 5 minute installation. They run on batteries and the only "wiring" you have to do is wrap a little wire around the spark plug lead.

 

[DaBears]

Yes MattFL it has that exact carb set up. Very little adjustment for idle air/fuel mix. It does idle very steady so not the same as you saw. I do agree that more adjustment could be key here.

 

[ahicks]

My thought - rich engines rarely quit. Point being, it's very likely this engine is starving for gas.

Another thought. I don't know anything about the automatic choke these little guys use, but my bet is it offers a completely different route for the fuel. That would account, maybe, for the fact it's working as well as it is - but just for a limited time. When the rich choke circuit shuts down, so does the engine. My bet is this is because there's an issue with the normal idle circuit.

You say you have a new idle tube, but wondering if the engine is able to pull fuel through it? Does it have a little o-ring at the top? If that's leaking the idle circuit will be sucking air - not the fuel it needs from the float bowl. Same story if there's an idle mixture adjustment screw. That has an o-ring that MUST seal as well - even if it's one of the tamper proof variety.

Bottom line - I'd pull it down again. See if you can follow the fuel trail from the float bowl to the tiny idle orifices near the throttle plate/butterfly.

Noteworthy maybe, is the fact that as many of these carbs as I've done, I STILL have to take one down a second or even third time on occasion to figure out what's going on.....

Best of luck!

 

[racerone]

Some trouble shooting needs to be done.-----Sounds like somebody had issues with the motor and sold it.----So before you start adjusting and guessing.----Do a compression test.-----Do a spark test.----Check valve clearance.----No beer tokens to spend doing some testing here.

 

[DaBears]

Thanks ahicks. The auto choke works as intended. When you start the engine cold it idles higher given the choke working then the choke piston extends as the motor warms and shuts that fuel passageway and the motor idles down exactly as it should. I tested the auto choke on a battery to make sure it works. It takes a couple minutes for it to extend the piston and when taken off the battery it takes many minutes more to retract. I don't believe this issue has anything to do with the choke.

Yes the idle tube does have a tiny o-ring. It was installed correctly and in place as far as I could tell.

Racerone I bought this boat/motor from a friend. He wasn't even selling it I was interested and convinced him to sell it. I can't imagine that he would knowingly sell it to me with these troubles but I guess it is always a possibility.

I am about to head out and try the idle screw adjustment in gear and will report back.

 

[racerone]

Sorry----Post #1 did not mention that it came from a trusted friend.

 

[DaBears]

So here is the results of my idle speed adjustment. I was able to get the stalling to stop by adjusting the idle screw. I increased it in gear to the point it stopped stalling. Again it was doing it exactly 1 min and 17 sec everytime until I got the RPM up. In gear it idles what I would think is acceptable mind you I am going by ear. Out of gear it would have to be said that it is a fast idle but certainly nothing crazy. Again all by ear.

Trolls too fast but I already knew that. I will pull a bucket behind me to slow it down until the lower pitch prop arrives. Will report back once that is on and I should be able to adjust the idle screw back some.

I can't disagree with any of your inputs on cleaning the carb again etc but to me that repetitive 1 min and 17 sec exactly was too much of a coincidence to ignore. Especially since I have seen a couple other posters saying the same time. To me, there is something that automatically shuts the motor off at that exact time. Could be different reasons I suppose but that consistent time is just too much of a coincidence IMHO.

 

[Sea Rider]

I am about to head out and try the idle screw adjustment in gear and will report back.

When performing the idle screw adjustment and the slow rpm screw if having one must be done with the combo floating on water, adjusting it on muffs, barrel would be OK as a starter, but will probally need to be readjusted once on water specially the slow rpm screw if counting with one.

Happy Boating​

 

[MattFL]

The 1:17 is definitely interesting. I would say make sure the idle RPM is within spec using a tachometer before spending too much time on other things. If adjustments are out of spec then things may not work as intended.

 

[DaBears]

As luck would have it the 7 pitch prop showed up. I put it on and went for a spin. As expected I was able to reduce the in gear idle RPM via the idle screw to just above the point that the mystery 1 min 17 sec stalling happens. So works like a charm now and trolls at a nice slow speed. At WOT the RPM's are now more in line with what I would expect (by sound). The added bonus is that the boat will now come up on plane. Probably could actually reduce the pitch a little more but I wouldn't do that until having the RPM monitored properly. So for now I doubt I will do anything except go fishing. Thanks for your folks feedback.

 

[Sea Rider]

As luck would have it the 7 pitch prop showed up. So works like a charm now and trolls at a nice slow speed. At WOT the RPM's are now more in line with what I would expect (by sound).

It's impossible to tell by sound not even having a fine tuned musician ear to know at which wot rpm the motor was running at...

Happy Boating​

 

[MattFL]

If you couldn't get on plane before then you were definitely way over propped! I'm really curious about the 1:17 thing, but all's well that ends well so enjoy some fishing!

 

[km1125]

I have an older 8HP Honda, but I believe it is the same as the newer 9.9s. I had a problem where the motor wouldn't idle, but would run at higher RPMs. If I started the motor and quickly got up to speed, I could run for miles. If I slowed down it was tough to keep it running and would frequently stall. I had a similar issue in a Tohatsu that ended up being electrical (charge coil was just BARELY out of spec), so after cleaning the Honda carb a couple times I as convinced it was an electrical issue.

Changed a few parts on the electrical side and got nowhere. Went back to the carb and cleaned it a THIRD time, including soaking it for 4 hours and still no dice. Took the carb off a FOURTH time and let it soak OVERNIGHT and the problem was GONE.

On all the small carbs I've worked with like these, I ALWAYS take out that non-adjustable plug for the idle mixture and put a normal one in (for the Merc/Tohatsu you just drill the plug out and the screw is underneath). I think that also helps in getting the soaking carb cleaner into the spots it needs to go.

 

[MattFL]

In regards to soaking; I've found that soaking in a hot ultrasonic cleaner can really help a ton, and I think the heat is a big part of that. For solvent in the ultrasonic cleaner I've been using WD-40, there might be something better but so far it seems to really do a nice job dissolving grease, oil and goo without damaging the metal. Just soaking in cleaner doesn't always get the tiny little passages clean, if they're really clogged the cleaner doesn't even seem to get in there. But the heat and ultrasonic part seem to do a better job of loosening that stuff up.

 

[pvanv]

In regards to soaking; I've found that soaking in a hot ultrasonic cleaner can really help a ton, and I think the heat is a big part of that. For solvent in the ultrasonic cleaner I've been using WD-40, there might be something better but so far it seems to really do a nice job dissolving grease, oil and goo without damaging the metal. Just soaking in cleaner doesn't always get the tiny little passages clean, if they're really clogged the cleaner doesn't even seem to get in there. But the heat and ultrasonic part seem to do a better job of loosening that stuff up.

Right. In my heated ultrasonic, I use regular carb dip (in 1 gal cans at the auto parts house), then after at least 6 hours, I blow out with generic carb spray. Works great.