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Discussion Starter · #1 ·
Hello everyone! I would really appreciate some advice here before I start tearing this thing down again. Here's the info:

Equipment: 2011 Cub Cadet (S/N) 31AH55KT596 2-stage with the 357cc OHV engine (83-series MTD engine).

Background: I picked this snowblower up a few months ago after it had been sitting for a few years and wouldn't start. I drained and filled the fuel tank a few times and cleaned/rebuilt the carb. After this it started up right away and ran great from idle to full throttle for the first 6 weeks of snow here. I used it about 4 times in that period and it gave me no indication at all that something was wrong with it.

Problem: I went to go start it after sitting for about two weeks and it would not run at all. It was spraying a bit of gas out of the exhaust. I couldn't troubleshoot at this point and left it to sit for a few days. When I went back to look at it again, I tried to start it and it would turn over but not run. Occasionally, it would run very rough for a few seconds and immediately die off accompanied by backfire and sometimes visible flame out of the carb. It would also backfire from the exhaust but not as frequently..

So now I'm wondering what I need to chase down first. Is this a valve lash issue? Sticking valves? Could the carb have gummed up again from something still in the fuel lines or carb?

Any help is greatly appreciated.
 

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Welcome to SBF hilderguy
173943


The backfiring through the carb sounds like timing.
It sounds to me like you may have a damaged key on the crankshaft allowing the timing to be off. This would be more likely if the last time it ran you sucked in something with the auger/impeller and forced the engine to stop suddenly.


.
 

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welcome to the SBF

have you removed the spark plug and looked at it? does it read F6Rtc or torch on it. if so replace it with a real ngk or the champion . the oem plugs from china are a little hit and miss,they work, don't work or miss fire

attached are the engine and owners manual to help you a little
 

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Discussion Starter · #4 ·
Welcome to SBF hilderguy View attachment 173943

The backfiring through the carb sounds like timing.
It sounds to me like you may have a damaged key on the crankshaft allowing the timing to be off. This would be more likely if the last time it ran you sucked in something with the auger/impeller and forced the engine to stop suddenly.


.
Thank you! Longtime lurker first time member over here. In the time I have owned it, I have not sucked anything up that forced the engine to stop suddenly or anything like that. Ran smooth as can be up until this most recent startup attempt. Is it still possible something affected the timing?
 

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Discussion Starter · #5 ·
welcome to the SBF

have you removed the spark plug and looked at it? does it read F6Rtc or torch on it. if so replace it with a real ngk or the champion . the oem plugs from china are a little hit and miss,they work, don't work or miss fire

attached are the engine and owners manual to help you a little
Thank you. The plug is an NGK. I pulled it when I was first trying to get the machine running before my carb rebuild, it was a little black but the electrode looked fine. I haven't pulled it since though.
 

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I had a similar issue with my MTD powermore engine. I was ATVs loss, and checked the ohv valve clearances,candy the exhaust valve was not opening. A part of the rocker arm had dropped off. I put it back on on it runs perfect. Half pull, and it starts every time
 

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Discussion Starter · #9 ·
I had a similar issue with my MTD powermore engine. I was ATVs loss, and checked the ohv valve clearances,candy the exhaust valve was not opening. A part of the rocker arm had dropped off. I put it back on on it runs perfect. Half pull, and it starts every time
Good to know thanks. I am planning on diving in to it again this weekend so will be sure to let everyone know what I find. Hopefully it's something obvious.
 

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Thank you. The plug is an NGK. I pulled it when I was first trying to get the machine running before my carb rebuild, it was a little black but the electrode looked fine. I haven't pulled it since though.
is that the OEM plug? if so change it anyway as a lot of plugs from china are really mislabeled as being something they are not. with a lot of forum members finding the same issue, PLUG STUDIO / NGK
a example is my own machine, it had a plug labeled bosch, wrong color blue and type used in the word bosch, on the steel was stamped f6rtc in tiny letters and the torch emblem . the motor ran, shut it off, failed to restart, .replaced the plug with a auto parts store boxed plug,1 pull restart .
 

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Discussion Starter · #12 ·
is that the OEM plug? if so change it anyway as a lot of plugs from china are really mislabeled as being something they are not. with a lot of forum members finding the same issue, PLUG STUDIO / NGK
a example is my own machine, it had a plug labeled bosch, wrong color blue and type used in the word bosch, on the steel was stamped f6rtc in tiny letters and the torch emblem . the motor ran, shut it off, failed to restart, .replaced the plug with a auto parts store boxed plug,1 pull restart .
I don't know if the plug was replaced before I owned it, but that's good to know. I will play it safe and replace the plug for sure. Sneaky aftermarket!
 

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Discussion Starter · #15 ·
Update: Pulled the old plug, it was indeed a legitimate NGK although not a bpr6es. It definitely looked fuel soaked. Replaced the plug with a new BPR6ES, gapped between 0.026"-0.030" and it started up right away. This makes me wonder what caused my original issue in the first place. My gut tells me the float is stuck and flooding the engine while it sits. Is it possible the carb gummed up again after my rebuild? I get a little bit of popping out of the exhaust (afterfire?) at full throttle and more at lower RPM but it does not stall out. I want to assume there is still an underlying issue but I'm leaning towards a fuel issue. Thoughts?
 
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