LB 5239 hunting for fuel? Or surging?

franchi

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Hello All:

My 5239 mower surges or hunts during use. It starts on the first pull but acts as if it is starving for fuel. Adjusting the needle makes no difference as I can turn the needle until it hits the bottom of the engine and no change! I just rebuilt the carb so it is very clean. The surging is why I rebuilt the carb!

Should I open the main jet by drilling it to a larger diameter? If so, how much? If this is not the fix, what else should I consider? The fuel is 16-1 and is fresh. Could fuel with excessive oil cause this problem? It really produces a large amount of smoke!

Perhaps it is not a fuel problem. Perhaps the governor is sticking or is loose or...

Suggestions and or comments?

Stay well,

Franchi
 

Rivets

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Before doing that, did you remove the main nozzle and clean it?
 

franchi

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Yes, everything is clean!

The fact that the needle Has NO effect on how the engine runs has me stumped. It has always worked in the past. A needle and seat can not be a mystery, can it? Turn it in= less fuel. Turn it out = more fuel! In this case, the needle does not make any difference.

What is happening?

Stay well,

Franchi
 

Rivets

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Yes, a too rich fuel mixture can be the problem. You might want to try the synthetic 2-cycle oils, which will change the mixture, but still keep the oils protection properties. I use Opti-2.
 

franchi

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I am now thinking that the fuel was stale. I mixed a batch of fresh fuel, and the problem ceased.

It is now a sweet running 52339!

Thanks for the replies.

Franchi
 
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