Carburetor Thermovalve Test

Fig. 71 Checking The Carburetor Thermo-Valve:

NOTE: The carburetor thermovalve switching temperature is 33°C (91°F).
1. With the carburetor below the thermovalve switching temperature ( not above 30°C/86°F), disconnect the hose at the carburetor thermovalve and connect a vacuum pump to the valve, Fig. 71.
2. Apply 260 mbar (7.8 in. Hg) vacuum to the thermovalve. Vacuum should remain steady. If the valve does not hold vacuum, replace it and re-test.
3. Start the engine and run until the carburetor is above the set opening temperature of the carburetor thermovalve (above 40°C/104°F).

Fig. 76 Checking The Carburetor Thermo-Valve:

4. Try to apply vacuum to the thermovalve with the vacuum pump, Fig. 76. The valve should not hold vacuum. If the valve does hold vacuum, replace it and re-test.