Chonda Carbeurators.

Messages
11,196
Location
NY Capital District
Ugh. So just got the snowblower back from sears yesterday. We brought it in to get the pull cord replaced (I broke it somehow, don't ask lol) and to have them fix the surging issue the engine has had since it was new. It's a Craftsman 26" (MTD) with the 208cc OHV "Craftsman" (Chongqing Vision Industry is the MFR) engine. Well, they replaced the pull cord, but it still hunts and surges at full throttle. The only way to eliminate it is to adjust the low idle speed screw, which means it can't surge, but there is no idle. It's full throttle or off. I managed to pull the carb off (Hyuai or something like that). And the gasket between the carb and the cylinder head is destroyed. Mutilated. Thinking maybe it was a vacuum leak issue, I made a temporary gasket out of a cereal box. Fixed? Nope. There is no mixture screw. There are two screws on the bowl, but both are strangely for draining the carb. Dunno why it needs two, but anyway. I wonder if it's a governer issue, but I can't see how. It's a few springs and linkages, and haven't been touched since we got it initially. I finally called sears parts and just ordered a new Carbeurator for $28. In the meantime, does anyone have any advice? I'm at my wits end with this thing. It blows snow great, but the hunting surging is an issue. One, it's just REALLY annoying. Two, it hurts snowblowing ability, especially in heavy stuff. Three, It's annoying. Four, I can't imagine it's particularly good for the engine, or belts for it to be doing this constantly. Five, did I mention it's ANNOYING? I've tried carb cleaner. Like I said I ordered a new carb so hopefully that will fix it, but if it doesn't.... Anyone have any advice? Addendum: Oh yeah, and for whatever reason, it ALWAYS needs choke to start. Even if I just ran it for twenty minutes, and I shut it off... It needs at least half choke to start. When cold, it starts first pull. When it's warm it takes two or three, and it backfires the first couple times. Ideas? Related?
 
Last edited by a moderator:

JTK

Messages
13,518
Location
Buffalo, NY
I would think a proper gasket between the carb and head would help. The slightest vacuum leak will cause what you describe. Joel
 
Messages
10,783
Location
Jupiter, Florida
If you have access to it, try Avgas 100LL. It contains no alcohols and it atomizes better. Often I have to jet leaner to run Avgas, even when compared to fuel with no ethanol. In some OPE engines, the use of Avgas is similar to enriching the mixture.
 

Nick R

Thread starter
Messages
11,196
Location
NY Capital District
Originally Posted By: Cujet
If you have access to it, try Avgas 100LL. It contains no alcohols and it atomizes better. Often I have to jet leaner to run Avgas, even when compared to fuel with no ethanol. In some OPE engines, the use of Avgas is similar to enriching the mixture.
Well, there is an airport about 2 miles down the road, but I wonder what they'd think if I showed up asking where the AVGAS Pump is with a jerry can. Plus, isn't leaded gas illegal in anything except planes?
 
Messages
36,520
Location
ME
Your carb is too lean. One of your drain screws is a filler where in another country it will lead to adjustment. Does it surge on half choke? Bet not. Does it surge under load? Probably not. So you're judging it under conditions, running at top engine RPM with no load, that the tool has no purpose doing. Yeah it shouldn't surge. I like mine alot. The governor is quick to react when I hit a wall of snow. A less surgy governor would not be as quick to keep things from stalling. As long as you have a new carb, try carefully drilling out the jet in the old one. I would search karting forums for the magic number.
 

Nick R

Thread starter
Messages
11,196
Location
NY Capital District
No, it surges under load. Badly. Not under like, maximum heavy load at the end of the driveway. But in a moderate load, you know like 6" of regular snow, it will do it badly.
 
Messages
16,002
Location
NE,Ohio
Where did you find snow to test this thing out since you got it back? MY 2cycle toro surges horribly.. but once you hit the snow and a load its perfect.. as soon as you back off the load it starts surging again (no throttle on this thing just a governor) This is with a brand new all metal 90$(#$%#$%#$%) briggs carb. I could probably mess with it but 90% of the time its running it has a load and works great. It does run alot better than with my soggy lawnboy model plastic carb It had 2 years ago. SO I guess my question is how can you adjust anything without a load? Note: I was looking at used ones and ALOT of people were unhappy with new sears blowers...seemed to be lasting less than 5 years .. some less then 3.
 
Last edited:
Messages
14,505
Location
Top of Virginia
A few comments. First, I think you may be confusing the governed engine speed with "full throttle". The only time that engine will truly be at full throttle is when it's under a severe load, at which time you said it runs pretty good. Any other time, even with light snow, the engine is likely not at "full throttle", but will use enough throttle to run at the governed speed. As it hunts for a no-load engine speed, you'll be able to see the governor shaft moving back and forth. You can hold that governor shaft steady with your hand, to force it to run at the "correct" speed, but the engine will likely die as a result because it'd be too lean. Many small engines will surge/hunt with no load because that's not the intended duty for them. You may need to run the engine at partial choke due to a lean carburetor...that will likely fix your hunting problem. And you may find that it runs just fine at half-choke all the time, even at full load. PS: there are two bolts in the carburetor bowl; one is a drain bolt and one attaches the bowl to the bottom of the carburetor.
 
Messages
16,271
Location
N.H, U.S.A.
my 8hp snow king hunted at mid throttle until the engine was broken in after 2 years 10 hours use. That ran rich and the mixture screw was "fixed". It must be screwed in all the way and seated for it to run ok. But that was not a chonda carb. Good ol tecumseh.
 
Messages
5,532
Location
Canada
Originally Posted By: eljefino
Your carb is too lean. One of your drain screws is a filler where in another country it will lead to adjustment. Does it surge on half choke? Bet not. Does it surge under load? Probably not. So you're judging it under conditions, running at top engine RPM with no load, that the tool has no purpose doing. Yeah it shouldn't surge. I like mine alot. The governor is quick to react when I hit a wall of snow. A less surgy governor would not be as quick to keep things from stalling. As long as you have a new carb, try carefully drilling out the jet in the old one. I would search karting forums for the magic number.
I fully agree approved Could the jet be dirty? If not, a VERY slight reaming will fix it.
 
Messages
5,120
Location
Pittsburgh,PA U.S.A.
1) There is probably a very small air hole behind the choke plate. That is the idle air. Spray cleaner in there, and or clean it with a single strand of fine wire. 2) If you do get it running good, you probably want to use some fuel additive like Sta-Bil, or RedLine SL-1, or SeaFaom, and or spray some WD-40 into that small hole after you are done running it each time. 3) You can test to see if an engine is running too lean by holding a non lit butane or nap-gas torch in front to the air intake with the gas on. The gas from the unlit torch will rich-en up the mixture because it is fuel, and you are replacing some of the air with fuel. If the engine improves when the extra fuel from the torch is added, the next step is to look at why the carb is not providing enough fuel. 4) A bad gasket on the carburetor float bowl will also make a carb run lean, and cause the problems you list.
 
Messages
5,120
Location
Pittsburgh,PA U.S.A.
PS: I have only used propane, some of the other gases burn hotter, so if you do use something other than propane, don't use it for too long of a time. You don't want to melt a piston.
 
Top