Idle Surge on Older Briggs and Stratton 8 HP Motor

sr73087

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Hi, I am experiencing an idle surge on my walk behind leaf blower. It runs great for the first 5 minutes and really moves the leaves very well. Then after 5 minutes of running the motor it will idle very very low and then rev back up. This will continue every 30 seconds or so and sometimes the motor will even die out. I am not sure what to really look for 1st.
 

EngineMan

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Can you post up the model and type numbers.
 

DaveTN

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First thing that I would do is drain the carburetor bowl and spray it out. If that didn't help, then I'd turn the fuel mixture screw counter-clockwise about 1/16 turn. See if that makes any improvement. If it needs more, then turn in small increments until you get it running properly. Then run some gas treatment like Sea Foam or Lucas through the gas tank. That shoul help some at least.
 

Rivets

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I would pull the carb and give it good bath or have it ultrasonically cleaned. When reassembling it, replace the float needle and seat. Have found that this works 90% of the time.
 

sr73087

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I would pull the carb and give it good bath or have it ultrasonically cleaned. When reassembling it, replace the float needle and seat. Have found that this works 90% of the time.

Where is a good place to purchase carb parts? I've typically always worked on fuel injected cars, so its fairly new to me.
 

Rivets

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I always recommend buying parts from a small engine dealer. Take your numbers with you and have them look up the parts needed. This way you have a face to talk to, if for some reason they are not right. They may also give some advice as to the best way to clean it.
 

Fish

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While you have the carb off, you should check your valve clearances, if the gasket on the valve cover/breather breaks, it is a cheap gasket.

I am guessing that you will find your clearances my be too tight. If that is the case, just adjusting the valves would get you by, but a proper
valve job would be the best cure..
 

sr73087

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I was at my local power equipment dealer yesterday and I mentioned the issue and he said the 1st thing he would check is the coil. Any merit to this opinion? Where would I find the manufacturers resistance specs?
 
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