Engine starts okay, has a rough idle but will not rev up to full throttle

BuffordT

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  • / Engine starts okay, has a rough idle but will not rev up to full throttle
Could be several things. Need to verify you have fuel, spark, air and compression.

1.Remove fuel line AT carb. Drain into a glass jar. Should have good flow here.
2.Take an old spark plug. Gap to 1/4". Ground the threaded area on the engine block. Should have a good blue spark.
3.Air is remove the air filter FOR TESTING ONLY.
4.Compression you will need a compression gauge.

Most likely you need a carb cleaning internally. Very well could be messed up throttle and governor linkages and springs. Need to verify all those springs are installed per your engine parts diagram.

slomo
Thanks! I will go through your suggestions and see what I find out! I appreciate your help!

BuffordT
 

slomo

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  • / Engine starts okay, has a rough idle but will not rev up to full throttle
Is she a runner yet?

slomo
 

slomo

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  • / Engine starts okay, has a rough idle but will not rev up to full throttle
Okay moving on......

slomo
 

BuffordT

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  • / Engine starts okay, has a rough idle but will not rev up to full throttle
Is she a runner yet?

slomo
I believe it is up and running now. When I went to see about the linkage or carb my father-in-law decided he was taking it in to a shop. Their finding
was the carb was bad.

Thank you for all of your help, I do apologize for not getting back to you sooner, I got confirmation it is running again Tuesday night!

This is a great forum for newbies like myself.
 

BuffordT

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  • / Engine starts okay, has a rough idle but will not rev up to full throttle
Okay moving on......

slomo
Follow-Up ... after your suggestion of cleaning the fins I did do that, so at least for this year it's been all cleaned out!
 

slomo

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  • / Engine starts okay, has a rough idle but will not rev up to full throttle
Follow-Up ... after your suggestion of cleaning the fins I did do that, so at least for this year it's been all cleaned out!
Remember, that is a yearly maintenance item on all mower slash small engines.

Also in your engine manual, decarbonizing the cylinder slash combustion chamber. Remove the head and get all that stubborn carbon out of there. Depending on how much you mow, typical home owner should do it say every 4-5 years or so. Commercial guys doing mega mowing probably ever 2 years.

If you don't remove the carbon, it obviously builds up. It will flake off and get between the piston and the rings and score the cylinder bore. That carbon is tough stuff. Head gaskets are cheap.

Your Brigs engine date code will tell you how old the engine is. Most likely it's time to do yours.

slomo
 
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