9.9 Honda idles fantastic, runs fantastic at high rpm. Dies at low speeds. HELP

[Kirby64]

Hello everyone,

So here we go! I have a 2010 honda 9.9 (babj-1002127). I got it out for the first time today and it started like a dream. It idles very smoothly and runs like a top at full throttle. Issue is, it suddenly dies at lower speeds. There is no indication it wants to die. No chugging or sputtering, it just quits. I did notice that when I was at low speeds, right around when it would die, I could try to rev it up and it would chug a little then go back to low speed and die shortly after. There was a small amount of older fuel in the tank, but almost none. I topped it off with 94 octane fuel. The fuel filter is clean, the oil pressure light was always green, motor was peeing properly. I ran out the gas line and drained the carb. I'm really hoping it's just teh fuel, but I would love to hear some of your opinions! Thanks so much!

 

[ahicks]

In my experience, rarely is it ever "just the fuel"......

Honda's (and other 4 stokes) work great when they have clean carbs, but when the carbs are dirty, well, not so much. The reason they work so well when clean is they have multiple paths for the fuel to take and depending on the throttle setting will use different paths or combination of paths to get exactly the amount of fuel required. If one of those paths isn't working right (dirty) then you're going to have a "hole" somewhere in your performance window. Usually the super tiny passages used in the idle circuit cause the most trouble. Here, suspecting the next one up from there.

Try choking it, just for a second, when it starts to die again. If that wakes it up, you have a fuel issue no doubt. If it's running OK at idle, and OK on top end, it's almost certainly a carb issue.

 

[Kirby64]

Great tips. I will try tonight. I'm going to add a little sea foam and see if that helps. If not, where can I find some good instructions on how to clean the carb? Thanks for your help!

 

[ahicks]

Youtube maybe for some generic or semi generic processes? I'll just warn that some of the openings you'll be cleaning aren't much bigger than a whisker (literally). You have to make sure they are ALL clear, and you can't force anything through them. If you try, you're going to be buying parts as they will no longer be sized correctly, which means it will not run correctly. This project requires finding the holes too, that need to be cleaned as well as cleaning them. It's not something you want to approach when you are in a hurry, and if it still doesn't run right when your done, you need willing to get in there and do it again! I've had some 3 and 4 carb engines take 3 tries to get them right, and I've been doing them a LONG time....

And Seafoam, at it's absolute best, takes at least 24 hours to do it's thing.

 

[Kirby64]

I took it apart and blasted out every single port I could find. Doing the same thing, maybe even a little worse now. Would you recommend I just soak the entire thing in seafoam? can I use break cleaner on it? would either of these destroy the gaskets? I have no more carb cleaner left and wouldn't mind giving it another go tonight.

 

[Kirby64]

OK I had another can and used the whole damn thing on the carb. Every single port has been thoroughly blasted. The engine is back to its normal ways. It will idle perfectly for about 10 minutes after the carb clean, then die for no reason. After that it only lasts about 3 minutes before it dies again. I did notice that the engine block is getting very hot. Too hot to touch for more than a second. No noted exhaust coming from the larger port on the back though, which is a high temp exhaust, right? A few things I noticed. I pulled a spark plug and it was a fouled at the end, enough to leave a slick black mark when touched. Lastly, when at idle, there is no water peeing out. the slightest hit on the throttle and it starts to come out. My test runs were done with the throttle going just a enough to get water circulating.Could this be a thermostat issue? thanks for your insight

 

[ahicks]

I'd be having a look at the pump for sure. Don't run it again until you confirm that the pump is OK. Getting that engine hot is REALLY hard on the gaskets, especially the head gasket. That's someplace you really want to avoid going if at all possible!

 

[Kirby64]

Well, it 100% not the carb. It been cleaned so well theres no restrictions anywhere in it. All jets are spotless etc. I'm really leaning towards the water pump. Is it possible for it to be weak at idle? Do I need to maybe adjust my idle a little higher to make it pee at idle? Problem is, its still dying even with a small flow coming out At low RPM the stream is very hot, and much cooler at higher RPM's. Any more advice guys?

 

[Kirby64]

Holly smokes I think I got it. The impeller assemble has a water tube seal on it to seal it where it connect with the water tube. This piece was missing! causing no tell tale water at idle, causing a high heat shut down. Will install part and report back. WISH ME LUCK

 

[ahicks]

Hopefully you didn't overheat a gasket and you'll be OK. Do keep an eye on your oil for a bit though. There are a couple of different gaskets that could allow some of that new found water pressure to squirt right into an oil passage - filling your crankcase with water.

 

[Kirby64]

That was the issue. oil is golden! got my motor back!

 

[ahicks]

Point was to make sure you are still "golden" after a couple hours of use.

 

[Kirby64]

yep, that was posted after 4 hours of trolling