Ryobi Blower Only Runs With Choke Closed

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I need some advice from the small engine gurus in this group.
The History:
My Ryobi 340BV blower ran fine all during the fall. Towards the end of the season, I had started it multiple times over the course of a couple of hours, so it was fully warmed up.
I shut it down for a few minutes and it wouldn't start back up. It turned over, but wouldn't start, no matter where I set the 3 position choke.
I tried to start it a few times over the next few days, making sure it was cold and following the cold start procedure. No luck, it wouldn't start.
It was the end of the season, so I dumped the gas and stuck it in the shed, where it's sat for the last 4+ months.
The Current Problem:
Yesterday I pulled it out, changed the spark plug, sprayed the carburetor with cleaner and put in fresh 32:1 gas/oil.
I pumped it up, closed the choke and it started on 3 pulls.
The problem now is that it only runs with the choke fully closed. As soon as I move the choke lever to Partial or fully Open, it gives up a deep throaty sound for half a second as it stalls. It's almost like a kill switch. There's no surging or rough running, it just shuts down.
I let it warm up until it started to labor a bit and then tried to slowly open the choke. As soon as the choke started to open, it stalled.
I can start it over and over again with the choke closed, but I obviously can't run it that way.
Any ideas would be appreciated.
Thanks!
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DerbyDad03 wrote:

The carb needs to be cleaned. There is probably something plugging a jet.
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Thanks for that.
Last night I drained the tank, poured in a few ounces of Mechanic In A Bottle and pumped it into the fuel system per the instructions.
It's supposed to sit over night, so maybe I'll get lucky and it'll clean itself - I don't have high expectations, but we'll see what happens.
If it doesn't help, I'll start pulling things apart.
Thanks again.
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Many years ago, I had a car that started acting like that. It turned out that the carb was loose, allowing air to leak in and dilute the vapors, hence only running with a closed choke. Check to see if the carb is loose or a vacuum tube is disconnected or broken.
Paul
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That's pretty close to what I was going to write. I've seen engines, typically Briggs or Tecumseh, the gasket between the carb and the engine is missing, or badly leaking. New gasket, and some Permatex #2b, non hardening, and the engine runs much better.
The other time I saw that was on a farm tractor, the farmer had taken off the oil bath air filter, and it would only run part choke.
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Did you run he carb dry in the fall, and push the primer after it died and restarted it to be sure the fuel bowl has no gas, I bet not, and your carb is varnished up and needs a clean-rebuild.
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The carbs on those small 2 strokes almost never have a bowl. But it is probably a clogged jet. If they are not very old you can often get away with reusing the gaskets. I would not expect your "mechanic in a bottle" to fix it but I suppose it's possible. Imho most of those things are snake oil, if gas won't disolve the problem, other stuff usually won't either. I suspect you'll need to disasemble the carb and blow out the passages and jets with some carb cleaner using that little red piece of pipe that comes with the carb cleaner. Occasionaly I run into ones where dried gas/junk has reduced the size of the main jet and I have had to clean it out with a small piece of wire.
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Thanks for the detailed response.
re: "The carbs on those small 2 strokes almost never have a bowl"
I pull the carb off last night and you are right, there is no bowl.
re: "I would not expect your "mechanic in a bottle" to fix it..."
It didn't. There was a slight improvement - I can actually start it with the choke open now but it only runs for a second or two unless I close the choke right away.
re: "I suspect you'll need to disasemble the carb and blow out the passages and jets"
To disasemble it, do I remove the small plate at the bottom - where one would usually find the bowl?
After that, I'll be able to blow out the jets, right?
Should I have a new gasket available?
re: "Occasionaly I run into ones where dried gas/junk has reduced the size of the main jet"
Identifying the main jet will be pretty obvious, right?
Thanks again.
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I suspect the plate you are talking about covers the small diaphram pump. These small carbs do not have the traditional float bowl because they need to operate in a variety of positions. They are called membrane carbs. You might be able to blow out the jets by removing that plate. Under it you will find a diaphram and some flapper valves as well. Crud anywhere in there could be a problem. I'm guessing you are trying to avoid removing the carb? I have been successful at removing these carbs and taking them apart without damaging the gaskets so I can reuse them. You need to be careful though and sometimes you just can't. The carb to the head gasket is simple and you can cut another one of those from gasket material if you have to. They are really pretty simple but ingenious devices.
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re: "I'm guessing you are trying to avoid removing the carb? "
No, I actually removed the carb last night to see if I could remove the bowl and clean the innards.
When I didn't see the bowl as expected, I just sprayed some carb cleaner into the "back end" (the hole that was up against the head) and put it back on.
It didn't change the symptoms at all.
re: "The carb to the head gasket is simple..."
I don't recall even seeing a gasket. There was a thin metal plate between the carb and the head that I had to realign to get the bolts through, but I don't recall a gasket. Maybe I just wasn't thinking about it and missed it.
Anyway, I'll take it off again, remove the bottom plate and clean that area also.
re: "You might be able to blow out the jets by removing that plate."
And if I can't? How else would I clean the jets?
Thanks again.
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Might be an o-ring. Seems like most of the ones I have worked on had some way of sealing the mating surfaces between the carb and the head. I'd suggest taking apart the diaphram pump and checking there. There may be some adjustment screws as well. Take those out. Then look down the throat and see if you can spray down the main jet from in the carb throat. There might be some other orifices in the throat for low speed/idle fuel supply, might as well try spraying down them too.
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re: "There may be some adjustment screws as well. Take those out."
I was hoping you weren't going to say that!
There are 2 "spring-wrapped" screws on the side of the carb.
Taking them out is easy. Putting them back in is easy.
Properly adjusting 2 screws that I have no idea do what may not be so easy!
The unit ran fine last year, so I'd really like to get it cleaned without having to "adjust" anything - assuming that a clogged jet or some other orifice is the problem.
Anyway, I'll play around a bit, but it might not until the weekend. My evenings are booked until then.
Thanks for sticking with me on this one and I'll be back with either good news or more questions!
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On Tue, 18 May 2010 11:56:01 -0700 (PDT), DerbyDad03

Carefully and gently count how many turns as you screw them until they hit bottom. Do not crank them hard!
When you re-install, screw them in gently until they hit bottom and then back them out however many turns you had to turn them before to bottom them out.
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On May 18, 3:22pm, snipped-for-privacy@dog.com wrote:

Exactly :-)
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I'd wager that one, or both, screws probably need adjustment. Keep track of the turns, for each, but when reinstalling try 1.5 turns on each. Is there an H and an L next to the screws?
Look up on Youtube on how to adjust the idle on a two-stroke.
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On Tue, 18 May 2010 10:33:13 -0700, DerbyDad03 wrote:

Just as a gotcha, make sure the plate (or any kind of gasket) is the right way round when you reassemble; I've seen a few engines where the plate/gasket can go in one of two positions, but one way round it'll block off the port coming from the engine that the carb needs to run the fuel pump (I got one thing in where previous owner had taken things apart to solve some problem and reassembled with the gasket the wrong way round).
If it's a little Walbro carb, I'm almost certain I have tuning instructions scribbled down on a bit of paper up in the 'shop. Debris gets in those things, rubber diaphragms go weak, needles wear, the seal between the carb and engine goes bad so they don't pump gas properly... I've developed a healthy dislike for small IC engines :-)
cheers
Jules
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On May 19, 9:00am, Jules Richardson

Funny, I'm the opposite. I love them. For a homeowner use the piston/ cylinder will last longer than most people. The 2 stroke design has only a handful of moving parts. I have a chain saw that is over 30 years old and still runs just as good as it did day 1. I have others that are over 20. They have tremendous power for their size and weight. The little carbs are all just about the same and a breeze to remove and clean. Keeping the gas clean, adding some stabilizer, and they usually will go years and years without any problems.
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re: "Keeping the gas clean, adding some stabilizer, and they usually will go years and years without any problems"
"Usually" is the operative word here.
I bought the blower off Craigslist at the beginning of last fall and it ran fine for the entire season until it just wouldn't start after a few hours of use.
I was more than 3/4 through the 2nd (3rd?) 1-gallon container of gas for the season so I don't think bad gas was the problem, unless an actual piece of debris got into the carb.
What I still find strange is that it wouldn't start at all a few months ago but now it starts but only runs with the choke closed. Yes, I changed the plug and sprayed the carb with cleaner, but I guess I'll never know why it wouldn't start last year since that's no longer the problem I'm chasing.
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Spaying carb cleaner in or around a still assembled carb is pretty much a waste of time unless the only problem is sticking linkage. And my 30 year old chain saw is on it's 2nd plug. Plug's don't go "bad" all that easily. Plugs do get dirty if you use too much oil but a few swipes with a wire brush is usually all that is needed. If the electrode is not visibly worn then the plug can be cleaned and reused. But I won't argue that these motors are not for everyone.
You have a carb problem. Debris or water has gotten into it. Something is clogged or stuck.
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On Wed, 19 May 2010 07:47:46 -0700, jamesgangnc wrote:

Yeah, I agree there (well, apart from the stray apostrophe ;)

The main issue I think is that it doesn't take much for them to go from working to dead - bigger IC engines tend to degrade gradually, but the smaller ones can work one day and be utterly dead the next.

I agree that's the most likely. It still sounds odd that there's no gasket between carb and engine.
Oh, one thing I heard recently was that some Ryobi engines have just a plastic crankcase cover, and the screws that hold it down work loose - it's the crankcase pressure which drives the carb's fuel pump, so once the crankcase seal goes bad the pump in the carb stops operating properly. Not necessarily relevant in this case, but it's something to keep in mind when working on the small Ryobi stuff.
cheers
Jules
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