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Why does a Briggs and Stratton 4.5 HP lawn mower engine surge?

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Answered 2015-03-01 03:59:27

Surging is the result of a "lean" fuel mixture, meaning too much air and not enough fuel. The problem is most likely a dirty carburetor or an air leak in the intake system. To fix, inspect the carburetor and intake manifold for cracks or looseness. Tighten all fasteners to ensure all seams are airtight. Clean out the carburetor with some carb spray and blow out all holes/orifices with compressed air. If problem persists, carburetor must be removed and disassembled/rebuilt.

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