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Finally got the mower running, now it surges.


Eazy123's Avatar
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05-16-15, 06:33 PM   #1  
Finally got the mower running, now it surges.

So my mower finally runs, thank God. Unfortunately it runs really hard, then sputters like it's a out to die, then runs hard again and rinse and repeat. I notice there is a small rod connected to a spring (governor?) that will keep moving in and out on its own and when it does, that's when the change in performance happens. I'm assuming this is what's responsible for allowing gas through the carburetor? I'm such a noob. Anyway I've attached a link to a pic.

https://www.dropbox.com/s/vnkshbbhgt...706_1.jpg?dl=0

 
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05-16-15, 06:38 PM   #2  
The linkage is connected to an air vane, and it is connected to both the throttle and the governor. There is no adjustment in any of those parts and they would not be part of the problem. If someone stretched the spring out, maybe. Based on the info you've provided, it's hard to say what the problem would be.

Bad gas? Water in the gas? Crusty carburetor gasket? Weak condenser maybe? Hard telling.

 
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05-16-15, 06:42 PM   #3  
How long does it run well before it sputters? In other words, have you timed the cycle?

 
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05-16-15, 07:56 PM   #4  
That's the governor arm, it's connected to a flyweight system inside the engine. When you see it move, it's because it's trying to give the engine enough gas to rev up, then once it does rev up, it throttles back to where the engine should maintain speed, but since the carburetor is clogged, it can't maintain speed at that spot, so it has to throttle up hard again. Cleaning the carburetor well should fix it.


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05-16-15, 09:39 PM   #5  
Thanks all! It's a brand new carburetor but I'll clean it well in the morning. It starts surging almost immediately after it starts. It goes from high to low maybe every 5 seconds. New gas.

The first time I had started it, I had left the air filter hose disconnected and it ran just fine, but after that it started surging, even with the filter disconnected (the air filter is totally clean).

Sorry to be such a pain about this mower, guys. You are all so helpful. I'll clean the carb in the morning and see how that works

 
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05-16-15, 09:55 PM   #6  
If it's a new carb, it could be because of an air leak. Is the o-ring still in place behind the carburetor?


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05-16-15, 11:19 PM   #7  
Yep it's still there. I'll make sure it's extra snug.

 
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05-17-15, 04:05 AM   #8  
Air leaks usually raise the idle & keep it raised. Did is start to sputter as soon as you replaced the carb?

 
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05-17-15, 09:43 AM   #9  
Yep, first start after replacing the carb. Only time it didn't surge was the first time I started it without the air filter.

 
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05-17-15, 11:08 AM   #10  
Not sure what happened, but I removed and reattached the air filter and it kicked in just fine and stayed steady.

 
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05-17-15, 11:10 AM   #11  
I would ensure the idle mixture screw is adjusted correctly. While running I would turn it in or out (probably in) maybe 1/4 turn and see if it helps smooth it out.

 
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05-17-15, 12:31 PM   #12  
Where would that be located?

 
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05-17-15, 12:45 PM   #13  
Pretty sure you will not find one on that engine.

 
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05-17-15, 01:08 PM   #14  
With no model # information or picture of the carb, its hard to say.

 
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05-17-15, 01:14 PM   #15  
https://www.dropbox.com/s/vnkshbbhgt...706_1.jpg?dl=0
Briggs engine on a Yardman, and I am all but certain there is no mixture adjustment.

If by some chance there is it would be under the bowl or body of the carb, a screw with a spring. There may be a similar looking screw but more likely for idle speed and not a mixture screw.

 
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05-17-15, 05:04 PM   #16  
Hm...I'll look for something like that. It's surging again but it's cutting which is a start. Didn't get around to cleaning out the carb again but will do so later. Just strange how the first time I started it today, it ran solid, now it's back to surging.

 
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05-17-15, 05:47 PM   #17  
Easy123, if it started when you replaced the carb, then it's definitely the carb. Look for the mixture adjustment & turn it counter clockwise. The idle should increase. If it starts to drop again, go clock wise until it gets to the richest point.

 
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