Lawnmower erratic idle

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  #1  
Old 05-30-04, 07:42 PM
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Question Lawnmower erratic idle

When my Noma lawnmower is at full throttle the engine idle is erratic. When at low throttle its stable.Its a 3.7 hp brigg and stratton engine 4 cycle engine. The air filter is clean, the oil level ok, the spark plug look fine.What do you think?
 
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  #2  
Old 05-30-04, 08:11 PM
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Sounds like where the Hi/Low fuel cross over inside the carb is gloged.Take the carb.off/apart and soak in chem-dip for 20-35 minutes,run a wire up tubes in center of carb.in/theough every hole(I use a torch head cleaner)
Blow off and out with compressed air,put together an back on.ajust to 1-1/2 from closed(if your carb.has an ajustment screw) crank engine and try out.

REPLY BACK WITH ANY PROBLEMS OR QUESTIONS.
 
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Old 05-31-04, 11:40 AM
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Hello P.A.T.!

Replace the carburetor diaphragm, and clean the carb, but don't soak it in the carb cleaner if it is plastic.
 
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Old 05-31-04, 01:16 PM
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Question

Thank you for your quick response. How do I go about cleaning this part the right way since I have two different opinions here?You mentioned the diaphragm has to be replaced and is it readily available for the doityourselfer?I never worked on a carburator before and I'am afraid I will screw up.Thanks
 
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Old 05-31-04, 10:09 PM
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You can use compressed air and automotive type aerosol carburetor cleaner to clean the carb. Wear eye protection 'cause if it gets in your eyes you'll know it!!! The reason I suggest not soaking it in chem-dip if it is plastic is because plastic can be deteriorated and/or distorted by chem-dip and similar solutions. Also, there is a pressed in jet in these carbs that can develop leaks when the plastic is distorted. This is one of the simplest carburetors you could work on, so don't worry. It's really very easy. Remove the screws that hold the carburetor to the gas tank and lift the carb off. Scrape the old gasket off of the tank and carb and clean out the carb. (the diaphragm is sandwiched between the tank and carb). Then install the new diaphragm the same way the old one was attatched, and put on the new gasket and screw it back onto the tank. Let us know if you need help...we'll be here.
 
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Old 06-01-04, 09:02 AM
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Smile

Thanks again for your quick response Cheese.I will start dismanteling the carb this weekend and I will let you know of my progress.P.A.T.
 
  #7  
Old 06-02-04, 04:26 AM
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Diaphragm

The Briggs part number you will need is 495770. This includes the diaphragm and gasket and is all you should need, other than a good cleaning.
 
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