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Snowblower Stalls


studiomule's Avatar
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12-03-07, 08:51 AM   #1  
Snowblower Stalls

I have a Craftsman 10hp snowblower, model 536.886331
I've rebuilt the carb, changed the spark plug, tightened the belts, and the machine still stalls the moment it encounters snow. If I take a small path of the snow it will 'throw' the snow about 4 feet. The engine is running at 3200 rpms with no load. I've adjusted the high speed screw to be richer, but it still stalls the same. The governor seems to be working, as I can push on the throttle control bracket when at full throttle and I can feel the governor push back against me. I've seen other posts say that the muffler can get carbonized and blocked, robbing power especially under load. Could this be the issue? Is there any problem to taking off the muffler to see how it runs? other than going deaf

 
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cheese's Avatar
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12-04-07, 01:18 AM   #2  
I don't reccomend trying to run it with no muffler. The muffler isn't the problem here anyway. I assume you are saying the engine stalls, not just the machine, right? If so, I'd say you have a carb problem. Try this, let it idle, then switch it to full throttle as quickly as you can. Does it respond by crisply revving, or does it bog and/or stall?


"Who is John Galt?" - Ayn Rand (Atlas Shrugged)

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12-04-07, 02:51 PM   #3  
snowblower stalls

Just a thought here. Sounds like dirt in a passage. When you rebuilt, did you clean the passages, bowl and ensure that the needle float is in properly? My experiences with carbs on Toro snowmachines taught me to make sure that the needle float was clean and to spay carb. cleaner through the passages. Just wear safety goggles and aim the ports opposite side away from you. Sounds like dirt in a passage.

Recently had similar problem on a leaf blower. Did all this over a clean white paper towel and was amazed at what came out. The blower is over 15 years old and still starts now on the first ( well maybe second )pull.

 
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12-04-07, 03:53 PM   #4  
Cheese,
I tried your suggestion. The lowest I can get the machine to run is 2300 rpm. Any slower and it stalls. And I need to go very slowly down to this speed or else it stalls. While at the lower speed the muffler spits blue flame; adjusting the low speed screw didn't seem to help. When revving throttle quickly the machine hesitated, spit flame, then got up to speed. At this point I guess I'm going to re-clean the carb. Is there any chance the linkages are incorrect? I thought that I replaced everything to where it was before I cleaned it, but I'm not 100%. I can't find any documentation showing how it should be set up. I posted photos of the linkage setup here:http://www.studiomule.com/snowblower
Thanks for your help

 
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12-04-07, 07:11 PM   #5  
On the 3rd pic from the bottom, did you loosen this screw on the governor arm? If so, did you reset the governor adjustment according to the manual?

If not, this could cause stalling, but still, from your description of how your engine is running, you definitely still have carburetor problems.


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12-05-07, 04:40 AM   #6  
I did loosen the screw. to reset I put throttle to full, turned governer tab clockwise as far as could go, and tightened. I'm going to soak the carb and see what happens. hopefully we have another light snow to test it on.

 
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12-13-07, 04:42 PM   #7  
snowblower still stalls

I have cleaned and soaked the carb and rebuilt, and the engine still bogs and stalls right away when encountering the smallest amount of snow. I've fine tuned the mixture screws and have made the mixture richer, but it does not help. The engine starts easily (electric start, I haven't had any luck turning the engine over by hand) and sounds like it is running strong (3400 rpm). Since cleaning the carb the engine will allow me to throttle down to idle without stalling. Could this be a compression problem? I haven't replaced the head gasket or checked the valves. I was hoping the carb soak would do the trick, but now it seems more serious. Ignition, points? Any ideas appreciated, I'm about ready to roll this thing down a hill.

 
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12-13-07, 07:44 PM   #8  
During the cleaning did you make sure the bowl nut(main jet) was clean (I usually use the wire from a twist tie), check the photo below. Have a good one. Geo

http://i190.photobucket.com/albums/z...c_bowl_nut.jpg

 
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12-14-07, 04:46 AM   #9  
it was the new nut that came with the rebuild kit, and then i soaked that with the carb as well.

 
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12-14-07, 04:49 AM   #10  
The other day after I reinstalled the carb there was some trace amounts of snow left from our last storm. I had the machine running to fine tune the carb, then it ran for about 10 minutes while I scraped a pile of snow together. It went through it fine without bogging and threw this icy snow about 25 feet. Is this is a sign that there's a bad seal somewhere? That after getting the engine warmed up it performs better?

 
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12-14-07, 11:33 PM   #11  
It does sound like maybe you should check the valve clearances, but first, does it now have the crisp strong accelleration when flipping the throttle from idle to full? If not, I'd still lean toward the carb.


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12-15-07, 08:02 PM   #12  
I ran it today and it again wasn't throttling down easily. I did notice something with the carb though. When I went to prime it, gas squirted out of a small pinhole in the side of the body of the carb. It's located to the right of the welch plug, near the mount for the heat cover. It looks like its meant to be there, but I don't understand why fuel would spray from here? Does this indicate a blocked passage way?

 
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12-16-07, 12:17 AM   #13  
You might just be ahead of the game to replace the carb. I think it is still the issue.


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12-18-07, 06:49 AM   #14  
Ok, so I soaked and rebuilt the carb for a 3rd time, but I think I've finally found the problem. I screwed the bowl nut into the carb without the bowl and realized how small of a tolerance there is for the holes to line up correctly, especially the small hole set higher in the threads. I made a reference point on the body of the carb so that when I attached the bowl I could get it back to the correct point. Low and behold, I was tightening about 1/4 turn tighter than this point on the previous rebuilds, effectively blocking out these holes. The machine will now idle fine, but I haven't been able to blow snow since all we have now is about 2" of solid ice. Am I correct to assume that this small adjustment could have been my problem? I do not see anything in the engine manual about the importance of this, but it seems painfully obvious now.

 
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12-18-07, 03:50 PM   #15  
The holes in the bowl nut don't line up with any other holes. They can be oriented 180 degrees away from the holes in the carb body and still work as intended. There is a gap in the area where the holes are, so there is nothing to block the flow of fuel from the hole in the nut to the hole in the carb body, no matter which way it's turned. I think you must have inadvertently fixed the problem during the rest of the process.


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12-19-07, 04:09 PM   #16  
got to test the blower out today. Once again, on the first prime the carb shot gas out the side body through the small pinhole near the heater box cover. The engine will idle down, but still stalls under load. What can go wrong inside a carburetor to make it go bad? Is there anything else to check before buying a new carb?

 
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12-19-07, 10:35 PM   #17  
I'm not sure what pinhole you're describing. There shouldn't be gas shooting out of a pinhole or anyplace on the carb other than the main fuel nozzle when you prime it. I don't know what differences there might be on a snowblower engine carb (I don't know much about snowblowers...we don't get snow here). Maybe there's something about the carb that I'm not familiar with. How does it run with this pinhole blocked? Maybe it's a hole that was plugged with a steel ball, and the ball came out? (common way of blocking a drill port on carbs).


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12-20-07, 07:08 AM   #18  
image of the pinhole i'm describing is here: http://www.studiomule.com/snowblower
I'll try to see if I can plug that hole tonight.
Thanks for your help

 
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12-31-07, 08:31 AM   #19  
Snowblower Stalls

Just fixed a similiar problem on a 5HP Tecumseh on a Sears snowblower. Turns out the crank to flywheel key was sheared. The flywheel had turned about 15-20 degrees from the correct location. This caused the ignition timing to be off. The machine started and ran good, but did not have power at high speed. It also acted as if it was running lean as flames would come out of the exhaust. The key on the 5HP was cast aluminum. It took us about 10 hours to find the problem. Don't know if this applies to your 10HP, but probably worth a shot.

 
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12-31-07, 12:31 PM   #20  
Posted By: studiomule image of the pinhole i'm describing is here: http://www.studiomule.com/snowblower
I'll try to see if I can plug that hole tonight.
Thanks for your help
If you have fuel squirting from that hole your float level is too high. Either the seat has broke down or got lost from cleaning. Either that or your float tab needs to be bent to drop the fuel level. I had the same problem from the exact same hole with an HM80 tecumseh I have. For me the needle seat got blown out when I cleaned the carb. When my engine ran it would run real rough and rich because it was getting too much fuel. I put a new seat in and the squirting went away. I'd drop the float bowl and remove the float/needle assembly and look down the bore the needle drops into. If there is just an empty bore and no rubber o-ring in it, thats your problem. Buy the needle & seat kit and install the seat. If there is a white o-ring in the bore, then I'd suspect the float height isn't correct.

 
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12-31-07, 07:44 PM   #21  
The hole you're talking about is the vent for the float bowl. It will spray fuel from this hole, (almost microscopic) if you're too pushy with the primer, or you have a blocked passage in the carb . When you say you soaked it, What did you soak it in?? Was it a carb bath or varsol or something else?? To me you have a passage blocked. Soak it in a proper carb bath, spray out with a spray carb cleaner & follow with compressed air. With a new kit It will run like New!! Let us know what you've been using for a carb soak. Have a Great Happy New Year, Roger

 
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