Briggs & Stratton 3.5 HP miss and rough run ?

george3

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Briggs & Stratton 3.5 HP A736008 MIN [SAE J607] Mower starts right up - runs fine for a minute then starts to miss and run rough - runs fine again for awhile just before it goes MT. Any suggestions to save me time trouble shooting appreciated.
 

ILENGINE

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How about getting us the model type and code off of the engine, so we can see what you are working on.
 

george3

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How about getting us the model type and code off of the engine, so we can see what you are working on.

Briggs & Stratton 3.5 HP A736008 MIN [SAE J607] This is what it says on the front of the motor cover. If that is no good please till me where I'm supposed to look for it ? Thanks.
 

ILENGINE

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The older briggs engines will have it stamped into the metal housing above the spark plug.
 

george3

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The older briggs engines will have it stamped into the metal housing above the spark plug.

Thanks - I'll check - what's all the numbers and letters on the front of the cover if you know ? Thanks.

I checked - don't see anything - pardon my ignorance - do I have to take the cover off to look for it ? Thanks.
 

ILENGINE

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The 3.5 and other numbers is the rated HP with the standard that was used to test it. Sometimes the model number info will be stamped above the muffler.
 

george3

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The 3.5 and other numbers is the rated HP with the standard that was used to test it. Sometimes the model number info will be stamped above the muffler.

OK - stamped above the muffler - Model 92502 Type 3105 01 Code 86052952. Thanks
 

ILENGINE

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I would start by replacing the diaphragm between the carb and tank. Could be related to the fuel pump part of the diaphragm or the auto choke part. If you haven't replaced the plug yet, that would be a suggestion also.
 

george3

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I would start by replacing the diaphragm between the carb and tank. Could be related to the fuel pump part of the diaphragm or the auto choke part. If you haven't replaced the plug yet, that would be a suggestion also.

Thanks for your time and knowledge. I'll give it a shot. Are you saying replace the diaphragm and the auto choke part or is the auto choke part, part of the diaphragm kit - in other words is it two different problems and two different part kits or one problem and one kit ? Just curious - why would it runs fine for a minute then starts to miss and run rough then run fine again for awhile just before it goes MT - So it runs great - misses - runs great ?? Thanks.
 

ILENGINE

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The carb diaphargm contains the fuel pump to pump fuel into the small well into the fuel tank, as well as the vacuum chamber to operate the auto choke. So you replace all the parts with just the diaphragm. the choke may be opening and closing instead of staying open when it is running. Or maybe not pumping fuel correctly, and causing it to run lean. Clean the carb while you have the tank/carb off the engine.

Just make sure to read the instructions that comes with the new diaphragm to preset the choke correctly.
 
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