Common Problems and Troubleshooting Methods for Thermal Fog Machines

Learn the most common thermal fog machine faults and troubleshooting methods, including startup failure, ignition problems, low spraying output, flameout issues, carburetor blockage, nozzle cleaning, and maintenance tips for thermal foggers.

After a thermal fog machine has been used for some time, it may fail to start or work improperly. When troubleshooting, check the machine step by step by inspecting the electrical system, fuel system, air system, and liquid system separately.

1. The Machine Cannot Start

(1) No Ignition Response When Pressing the Ignition Switch

If there is no ignition when the switch is pressed, connect the two wires under the switch directly to test it.

  • If ignition appears, the switch is faulty and should be replaced.

(2) The Switch Works but the Spark Plug Does Not Ignite Properly

Check the spark plug for:

  • Excessive carbon buildup
  • Damage or breakdown
  • Water contamination
  • Excess oil

Clean or replace the spark plug if necessary.
After installation, the machine should start normally.

Note: For two-stroke engine spark plugs purchased on the market, adjust the spark gap to 2–3 mm before use.

(3) The Switch and Spark Plug Both Fail to Ignite

Inspect the high-voltage wire and ignition coil/switch.

Connect the high-voltage switch to a new battery and test whether a spark is produced by touching the neutral wire and live wire carefully.

  • If there is no spark, replace the damaged component.

(4) Ignition System Works but the Machine Still Cannot Start

Check:

  • Battery connection
  • Battery power level

Connect the charger to a 220V power supply and connect it to the machine. Hold the ignition switch while charging.

(5) The Machine Ignites but Still Does Not Start Properly

Check the following:

  • Whether the gasoline grade is at least 93#
  • Whether the carburetor or filter cup is blocked by dirty fuel

If blocked:

  1. Loosen the carburetor adjustment screw.
  2. Use compressed air to remove impurities.
  3. If necessary, disassemble and clean the carburetor.

Replace damaged carburetors or filter cups if needed.

Using low-quality gasoline may also prevent proper combustion and starting. Replace it with suitable fuel.

2. The Machine Produces Little Fog or Stops Spraying After Use

(1) Check the Air Pipeline and One-Way Valve

Inspect whether:

  • The gas pipe is cracked or leaking
  • The one-way valve is blocked by impurities

If air flows backward, clean or replace the valve.

A damaged one-way valve can reduce pressure inside the chemical tank, preventing liquid from being sprayed.

(2) Check the Carburetor Diaphragm

Inspect whether the carburetor diaphragm near the base is damaged.

  • Replace it if necessary.

(3) Check the Nozzle and Protective Pipe

Look for heavy carbon deposits inside or outside the nozzle and protective tube.

  • Clean them using a cleaning rod.

Also check whether the chemical tank lid is tightly sealed.

  • Air leakage can prevent pressure buildup and stop liquid spraying.

If the chemical mixture is too concentrated or powder-based:

  • Add more water for proper dilution.
  • Powder chemicals should be diluted twice before spraying.

Generally:

  • 1 kg of powder chemical should be mixed with 8–10 kg of water.

Improper dilution can damage crops and block the spraying system.

(4) Check Whether the Liquid Path Is Blocked

Inspect the liquid line and spray pipe for blockages.

  • Clean them promptly using a metal rod or suitable cleaning tool.

(5) Check the Gas Check Valve Connected to the Chemical Tank

Inspect for impurities inside the valve.

  • If air flows in both directions, the valve is faulty and should be replaced.

When reinstalling:

  • Make sure the check valve is not installed backwards.

3. The Machine Easily Stalls After Opening the Chemical Valve

(1) Check the Carburetor Diaphragm Again

If the diaphragm is damaged or not tightly connected to the base plate:

  • Replace it immediately.

There should be no gap between the diaphragm and the base.

(2) Check Whether the Nozzle Is Burned Through

Burn damage usually occurs when the machine runs without spraying for too long.

Important:
The machine should not run empty for more than 2–3 minutes.

(3) Adjust the Carburetor Oil Circuit Screw

If the machine still stalls after all inspections:

  • Adjust the carburetor fuel adjustment screw properly.

Recommended adjustment:

  • Tighten fully, then loosen by 2.5–3.5 turns.

Further adjustment may increase fuel supply and improve operation.

wrindu
wrindu

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