Fuel System Troubleshooting

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Engine cranks but won't start[edit | edit source]

  • No fuel to carburetor
  • Engine flooded with fuel
  • No spark at plug (ignition system faulty)
  • Clogged air cleaner
  • Intake air leak
  • Improper choke operation
  • Improper throttle operation

Engine idles roughly, runs poorly or stalls[edit | edit source]

  • Improper choke operation
  • Ignition malfunction
  • Fuel contaminated
  • Intake air leak
  • Incorrect idle speed
  • Incorrect pilot screw adjustment
  • Low cylinder compression
  • Choke stuck open
  • Rich mixture
  • Lean mixture
  • Clogged carburetor

Misfiring during acceleration[edit | edit source]

  • Ignition system faulty
  • Lean mixture

Afterburn during acceleration[edit | edit source]

  • Ignition system faulty
  • Lean mixture

Poor performance (driveability) and poor fuel economy[edit | edit source]

  • Fuel system clogged
  • Ignition system faulty
  • Air cleaner clogged

Afterfiring[edit | edit source]

  • Ignition system malfunction
  • Carburetor malfunction
  • Lean mixture
  • Rich mixture

Lean mixture[edit | edit source]

  • Clogged fuel jets
  • Faulty float valve
  • Float level too low
  • Blocked fuel fill cap air vent hole
  • Clogged fuel strainer screen
  • Restricted fuel line
  • Clogged air vent tube
  • Intake air leak

Rich mixture[edit | edit source]

  • Clogged air cleaner
  • Worn jet or needle jet
  • Faulty float valve
  • Float level too high
  • Choke stuck open

Incorrect fast idle speed[edit | edit source]