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Noma/Tecumseh Snowblower Backfire/Stall


BikerBill's Avatar
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02-05-06, 06:52 AM   #1  
Noma/Tecumseh Snowblower Backfire/Stall

I have a Noma snowblower with a 12 HP Tecumseh OHV engine. It starts and runs fine under normal conditions. But in heavy, wet snow conditions the engine backfires loudly and will stall out and stop if I don't stop feeding snow into the auger. The carburetor has two adjustable jets, idle and main. I checked the main jet and it's set at one and one-half turns out, which seems reasonable. I didn't bother checking the idle jet since idle is not a problem. The person from whom I bought the snowblower (used) claims he had the unit professionally prepared for off-season storage. Since I have owned the unit, at the end of the season I run it dry of gasoline and then use the fuel dump valve to empty the bowl. So I have no reason to think the carburetor is gummed up.
I don't know if this related or relevant but I did notice an oil film over parts of the engine and snowblower. I checked the oil breather assembly and it seems fine. The problem may just be related to the fact that the valve cover screws had loosened up quite a bit and oil was escaping from around the rubber gasket.
I did not check for a broken flywheel key but have no reason to suspect it's broken. So if I don't have a lean fuel situation or ignition timing problem, what else can I check? Should I just open the main jet a quarter or half turn and see if that fixes the problem? And if it does then soak the carburetor in a cleaner bath? Something else?

 
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mla2ofus's Avatar
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02-05-06, 09:46 AM   #2  
Try opening the main jet a1/4 turn at a time and try it under load. If it starts making black smoke,turn main jet back in to original setting and check float level. Some one correct me if I'm wrong, but I believe float should be parallel with carb body while holding it upside down. Before removing carb, check bolts that attach intake manifold to engine block.Also check condition of spark plug, and check that it has a good blue spark. If spark is yellow or you can barely see it,it might be getting too weak under load.
Hope this helps,
Mike

 
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02-05-06, 09:52 AM   #3  
After re-reading your thread, I think the problem will be spark or plug related. Could also be an obstruction between gas tank and float needle valve giving it enough gas to run until engine requires more under full load.
Mike

 
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02-05-06, 05:35 PM   #4  
Mike,
I forgot to mention that I did check the bolts that attach the carburetor to the engine and they were very tight, so I don't think the mixture is getting leaned out by a poor seal to the engine. I haven't looked at the spark yet so I will try that next. And I will also try enriching the mixture by opening the main jet a bit. At the rate non-winter is going in the Northeast that may take a little while to try out under load.

 
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02-07-06, 03:05 AM   #5  
If the carburetor adjustment doesn't help then I'd say you need a carburetor reconditioning (in a quality bath cleaner (I like NAPA's)) using a Tecumseh rebuild kit and new mounting gasket. If, on the carburetor adjustment, you have to go more than 1 3/4 turns out then you have a restriction there and need to soak it.

 
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02-16-06, 08:12 AM   #6  
Any results yet, Bill?

 
BikerBill's Avatar
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02-18-06, 06:24 AM   #7  
Noma/Tecumseh Backfire/Stall Update

Nothing to report yet. I'm still waiting for a heavy snowfall to try out the suggested carburetor main jet adjustment. The problem only occurs when the unit is really heavily loaded by heavy wet snow. At the rate things are going here in New England I may have to wait a while.......

 
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12-12-08, 07:17 AM   #8  
Same problem here! Tecumseh stalling

Hi All,

I'm new here. I have the same problem with my 3 year old Troy Built - Tecumseh. It has done this since the first time I used it. I've tried the main and idle adjustments, no luck. Any other ideas? Snowing cats and dogs here today.

Thanks,

Jeff

 
indypower's Avatar
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12-12-08, 07:53 AM   #9  
A 3 year old engine does not have any adjustment screws. EPA rules mandated fixed jets in the mid 90's. If yours has adjustment screws then the carb or engine has been replaced.
Sounds like carb needs a cleaning.
Watch out for those cats!!

 
BikerBill's Avatar
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12-15-08, 07:30 PM   #10  
Jeff,

I tried the main jet adjustment but that didn't fix the problem. I completely disassembled the carburetor, soaked it in lacquer thinner, and then rebuilt it using the rebuild kit from Tecumseh, as Puey suggested. That did the trick.

My unit is about 15 years old so it's probably not surprising the carburetor was gummed up. With yours being only 3 years old I wouldn't suspect a gummy carb unless you don't properly prepare the engine for off-season storage. Since you said it's misbehaved from the time you've owned it it's hard to see how it could have a gummed up carb. Sorry but I don't have suggestions for you. Good luck.

 
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