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Curtis B.
Curtis B., Technician
Category: Small Engine
Satisfied Customers: 28064
Experience:  have worked on and around most engine models for 35 yrs./Polaris ATV expert
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Briggs and Stratton Model # 44M777 seems to be running very

Customer Question

Briggs and Stratton Model # ***** seems to be running very rich at high rpm but as soon as it is returned to idle runs great will also start good. I have had the carburetor rebuilt.
Submitted: 1 year ago.
Category: Small Engine
Expert:  Curtis B. replied 1 year ago.

Have you ran a cylinder test? Loosen the spark plug wires and with engine idling, remove one wire at a time, engine should continue to run. If engine dies when one wire is removed, the opposite cylinder is not firing. With only one cylinder firing, the exhaust seems rich. It may not be running on one cylinder, but it is a common problem with twin engines.

Customer: replied 1 year ago.

removed wire one at a time stayed running on both. Idles good starts right off everything is ok until about 1/4 to 3/8 throttle then starts to miss real bad and blows out black smoke. Pulled plugs they are very black sooty looking. Could something have been done wrong on carb rebuild to cause this?

Expert:  Curtis B. replied 1 year ago.

Choke flap in carburetor loose? May not be staying full open.

Expert:  Curtis B. replied 1 year ago.

see question still open, did you get to check the choke?