RPM SURGE

fastcat

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May 6, 2018
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I've got two pushmowers . 3-1/2 H.P. Briggs and Stratton engines . After about five to ten minutes of mowing the engine rpm will nosedive , not stall just slow down . I wait just seconds and the rpm's return and black smoke comes out of exhaust .This keeps repeating until I'm done . What is the fix ? Thank You !
 

slomo

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Jul 14, 2019
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Failing ignition coil or dirty fuel tank with a partial fuel line clog?? Carb needle and seat or float adjustment needed??. Air, fuel, spark and compression need verified.

slomo
 

Charlie8d

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Apr 26, 2021
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Fuel system problem. You may have to clean/replace fuel lines, carb, & tank, then add a filter.
 

bertsmobile1

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I think we need to know the models so we will know which style of carb you have .
Some can flood & some can not flood.
Could be as simple as a water build up in the bowl
If it has a choke, could be a faulty choke return spring
But was are guessing untill we know what we are looking at .
 
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