3. Engine Flooding
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Stuck float or needle valve
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Leaking float (brass floats can fill with fuel)
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Incorrect float height
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Missing or incorrectly installed float valve clip
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Excess fuel pressure overwhelming the needle valve
4. Hesitation or Bog on Acceleration
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Weak or torn accelerator pump diaphragm
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Clogged pump discharge nozzle
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Air leak in accelerator pump circuit
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Missing or incorrect check ball in pump system
5. Poor Fuel Economy / Running Rich
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Float level too high
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Choke sticking partially closed
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Main jet too large (or incorrect for altitude/application)
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Idle mixture too rich
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Power enrichment valve stuck open (if equipped)
6. Surging or Hunting at Cruise
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Vacuum leak in intake or carburetor base
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Lean mixture due to clogged main jet or restrictions
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Weak or improperly adjusted throttle return spring
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Worn throttle shaft causing air leak
7. Fuel Dripping from Venturi at Idle
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Excessive fuel pressure
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Float level too high or float valve not sealing
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Main discharge nozzle leaking when it shouldn’t (check discharge ball and spring)
8. Won’t Reach Full RPM / Power Loss
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Restricted main jet or emulsion tube
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Vacuum leak under load
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Partially blocked fuel line or filter
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Weak fuel pump not supplying enough fuel at high demand
9. Stalls When Coming to a Stop
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Idle set too low
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Idle mixture too lean
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Fuel slosh or low float level cutting off fuel momentarily
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Sticky throttle linkage or worn return spring
10. Backfiring Through Carburetor
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Extremely lean condition (vacuum leak or clogged jet)
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Incorrect ignition timing
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Intake valve issue (burned or sticking valve)
