Tag Archives: forklift spark plug error'

Failure Reasons for Forklift Spark Plugs

This blog post will contain five possible reasons on why your spark plug is failing. These reasons include: carbon fouling, oil fouling, overheating, pre-ignition, and insulator breakage. Visual and written descriptions will be provided for each possible reason.

Normal Condition

Appearance:

  • The base of insulator becomes white or gray when using unleaded gasoline
  • Electrode may become burned
  • The base of insulator becomes light brown when using leaded gasoline
Normal Condition

Carbon Fouling

Appearance:

  • Dried carbon deposited covering insulation base as well as electrode area

Engine:

  • Faulty engine stability at low speeds
  • Engine may die often
  • NOTE: nearly 90% of engine problems are a result from carbon fouling or oil fouling on forklift spark plugs

Causes:

  1. Incorrect thermal value
  2. Idling of the engine for too long / driving in cold temperatures
  3. Rich air-fuel mixture
  4. Clogged air filter
  5. Delay in ignition timing

Fixes:

  • Causes 1 or 2: use spark plug with a thermal value that is one level lower OR adjust engine idling.
  • Causes 3-5: perform complete readjustment and tune-up
Carbon Fouling

Oil Fouling

Appearance:

  • Base of insulator and electrode becomes shiny black; covered with oil or gasoline

Engine:

  • Faulty engine stability at low speeds
  • Engine may die often
  • NOTE: nearly 90% of engine problems are a result from carbon fouling or oil fouling on forklift spark plugs

Causes:

  1. Leakage of oil into combustion chamber from frictional wear of piston rings, valve guides, or cylinder wall.
  2. Rich air-fuel mixture

Fixes:

  • For cause 1: if forklift spark plugs become wet, simply clean the plug and reinstall it. If not, the engine requires a complete overhaul.
  • For cause 2: adjust the carburetor.
Oil Fouling


Overheating:

Appearance:

  • Base of the insulator will be burned and will appear bleach white from the heat
  • Electrode will be burned and become white / dark purple

Engine:

  • Engine horsepower decreases and speed falls when running at high speeds continuously as well as: driving for a long time uphill, or pulling too great a load

Causes:

  1. Incorrect thermal value of plug
  2. Use of low octane gasoline
  3. Ignition timing set too early
  4. Inappropriate cooling
  5. Poor air-fuel mixture

Fixes:

  • Cause 1: use a spark plug with a higher thermal value
  • Cause 2: use higher octane gasoline
  • Cause 3: adjust ignition timing
  • Cause 4: check the cooling system
  • Cause 5: adjust the carburetor
Overheating

Pre-ignition:

Appearance:

  • Electrode will be melted
  • Base of insulator is also melted, in extreme cases

Engine:

  • Caused by overheating
  • Temperatures in combustion chamber increase rapidly – destroying the spark plug as well as the piston head

Causes:

  1. Incorrect thermal value of plug
  2. Use of low octane gasoline
  3. Ignition timing set too early
  4. Inappropriate cooling
  5. Poor air-fuel mixture

Fixes:

  • Cause 1: use a spark plug with a higher thermal value
  • Cause 2: use higher octane gasoline
  • Cause 3: adjust ignition timing
  • Cause 4: check the cooling system
  • Cause 5: adjust the carburetor
Pre-ignition

Insulator Breakage:

Appearance:

  • Base of insulator has vertical crack
  • Appearance is similar to problems with overheating or lead fouling

Engine:

  • Engine horsepower decreases and speed falls when running at high speeds continuously as well as: driving for a long time uphill, or pulling too great a load

Causes:

  1. Incorrect thermal value of plug
  2. Ignition timing set too early
  3. Inappropriate cooling
  4. Poor air-fuel mixture

Fixes:

  • Cause 1: use a spark plug with a higher thermal value
  • Cause 2: adjust the ignition timing
  • Cause 3: check the cooling system
  • Cause 4: adjust the carburetor
Insulator Breakage

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Q14R-U11


Post by Intella Liftparts