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Discussion Starter #1 (Edited)
I have a toro 621 power clear snow blower (163cc) that starts on the first pull. It runs well on half choke until it warms up. Push the choke in and it continues to run well. After about ten minutes the engine begin to purge a little, not too bad. Then is stalls out. One pull and it starts right up again. Runs for a few minutes and begin to surge again and dies again. Does this weather its under load or just sitting.
While it is running there is occasionally a very slight backfire or pop. .

I Have replaced the spark plug, changed the oil and replaced the carburetor. None of these measures have seem to make any difference. I have checked the valve lash and the exhaust valve was a little tight (0.15 )
Spec says 0.20

I have checked the fuel cap and the fuel tank for venting and flow and all seems normal.

Does any smart person here have any ideas ?

Thanks
 

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I have checked the fuel cap and the fuel tank for venting and flow and all seems normal.
These were my first thoughts. Just to avoid any assumptions on my part:
- Loosening/removing the gas cap didn't help?
- You're getting good fuel flow from the line, if you disconnect it from the carb? This helps show that you don't have a clogged fuel filter, etc.

After it stalls, are you still getting spark? I'm guessing yes, if it will re-start so quickly. After it stalls, if you spray some gas/starting fluid/carb cleaner into the carb's intake, will it run from that?

Will it keep running if you push the primer as it starts to die? Does adding choke help anything as it starts to falter?

An obvious starting point, if these don't show anything, would be to adjust the exhaust valve clearance. It's possible that, as it heats up, the exhaust valve is not closing fully. But sometimes that shows up as a glowing muffler. I wouldn't have expected it to just cause stalling like that.
 

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It sounds like fuel but it seems like the only thing you didn't change is the ignition module. I have seen them do some weird things. Once had one that would only fail after running about 10 minutes under load but the machine would immediately restart in that instance too.


Take the body shroud off and the air filter box cover off and stand there with a can of something flammable. When it starts to die out give it a shot down the intake and see if it tries to keep running. If yes then fuel if no then its lost spark.
 

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Discussion Starter #4
Thanks for all your comments and suggestions.

Removing the fuel cap made no difference.
The fuel filter was replaced with the carb.
Fuel flow at the carb is good and appears there is no restriction.

Again there is a slight surging right before the engine dies. Not sure what that means if any thing.
The engine starts up with one pull immediately after the engine dies.

I will try pushing the primer bulb when the engine begins to surge and die.
I will also try the shop of starting fluid when the engine is dying to if that makes any difference.

Again thanks for all your help. Will get back to you with the further results.
 

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Surging as it dies is often indicative of running lean, and running out of fuel.

You could compare by closing the fuel shutoff and running until it dies (maybe around a minute), and see if it's the same behavior.

Is there a filter in the tank? My OHV Tecumseh has a filter screen inside the tank, at the outlet. I suppose it's possible that something is floating around in the tank, and occasionally blocking the outlet.
 

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Discussion Starter #6
Well.... We got about 2 inches of snow last night.
So I filled the snow blower with fuel and it started on the first half a pull.
Let it warm up for about thirty seconds on half choke and started to blow snow.

The snow blower worked great. No stalling. Some surging but not bad. Each time it began to surge I got ready to hit the primer button but never had to. It seems that the minor backfiring was gone also.

I must admit that I am puzzled.

Did a full tank of gas make a difference ?
Did it fix itself ?
 

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Well, I doubt it "fixed itself"....lol. I've been looking for pieces of power equipment that came with that option for years, and have had no luck. :wink2:


You didn't mention in your list of things in servicing the machine, draining the gas tank. Is it possible there was a fair amount of water or other contamination in the tank that has now worked its way through, or is temporarily hiding amongst the new gas?


Anyways...good to hear that it seems like it is running well again! :thumbsup:

.
.
 

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Discussion Starter #8
Yes the magical if not mystical " Fixed Itself " feature. Only available on the in your dreams model.

No, I removed the tank and drained it completely when I installed the new carb and gas filter.
Carb kit actually came with a new fuel line and primer line and clamps. Might as well use them.

Stay tuned for further updates.

Thanks to all
 

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I have the same problem but I do not have backfiring. I put in a new carburetor, check the spark plug for wear and cracks, cleaned and gapped it. I also ran it with gas cap off and same problem. I am using new gas and I replaced the inline filter. I did not get the magical fix.
 

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Welcome to the forum! Have you checked your valve clearances? They are pretty easy to adjust on an OHV engine. But clearances that are too-tight can cause problems as the engine warms up. Does adding partial choke help your situation at all?
 

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I fixed my problem. Last fall I noticed my gas cap was coming apart and I ordered a new one but never found the center metal screw of the old one. Today I found it, wedged in the drain of the gas tank. Removed it and snowblower works like the day I bought it. Close this trouble out!
 
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