lawn boy model #8073 surging

blackchevy3de

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my mower starts great and runs fine at idle and mid way but at full wide open its surging, don't want to drill out jet .
 

BlazNT

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Has it always surged in WOT(wide open throttle)? If not then what is happening is you are not getting enough fuel what you are a full throttle. This can be from different things but it all has to do with fuel delivery.

1. Clean out your fuel tank. Make sure nothing is in it. Use that gaS in your car or truck along with the fuel from your gas can.
2. Clean your gas can as well.
3. Replace all fuel line with ethanol fuel line.
4. Clean your carb. Lots of videos on how to clean your carb on youtube.

Report back and let us know how it worked. It is almost always your carb being dirty but with ethanol fuels now your fuel system could be causing the problem with the carb being dirty.
 

Lawnboy77

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I agree with the above reply, but want add a note. Don't forget to check for air leaks at the carb mating flange. I think that one has a metal Walbro so it's not as likely to warp like the plastic carbs, but worth checking out. Could be a faulty gasket as well.
 
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jp1961

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Ok,,,agree with all of the above, but adding one more item to check. The throttle shaft to carb body play, I heard can also be the culprit for surging.

Regards

Jeff
 

blackchevy3de

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Has it always surged in WOT(wide open throttle)? If not then what is happening is you are not getting enough fuel what you are a full throttle. This can be from different things but it all has to do with fuel delivery.

1. Clean out your fuel tank. Make sure nothing is in it. Use that gaS in your car or truck along with the fuel from your gas can.
2. Clean your gas can as well.
3. Replace all fuel line with ethanol fuel line.
4. Clean your carb. Lots of videos on how to clean your carb on youtube.

Report back and let us know how it worked. It is almost always your carb being dirty but with ethanol fuels now your fuel system could be causing the problem with the carb being dirty.

I will try that and get back to you thanks,ps I cant say if its always surged as I just picked is one up, what would it be if it has,
 

BlazNT

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I will try that and get back to you thanks,ps I cant say if its always surged as I just picked is one up, what would it be if it has,

If it has always surged it normally means you will have to widen the jet. I would never use a drill to fix it but a drill bit with your fingers.
 

blackchevy3de

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If it has always surged it normally means you will have to widen the jet. I would never use a drill to fix it but a drill bit with your fingers.

what size drill bit is used,
 

BlazNT

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You measure the opening and go 1/10,000 larger till it works. Every mower is different so you take it slow or it will get too much gas.
 

Lawnboy77

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I think that 8073 can be made to run great without enlarging the main jet. You can adjust the mixture to your liking with the one scew on the front of the carb once you get it clean and you can confirm there are no air leaks. The 8073 is old school Lawnboy F series, no need to modify the carb on this one.
 

Lawnboy77

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Don't forget to clean the fuel inlet screen on that Walbro carb. If you aren't familiar with the setup it's kinda easy to miss it. Just pull on the little brass ring at the inlet nipple and it should pull out...it's about 3/4" long. 9 times out 10 the fuel restriction is within this screen. That screen should be opened not collapsed to. If collapsed it will clog up much faster.
 
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