Why can't the vacuum film carburetor be installed?

The vacuum membrane carburetor cannot be installed for the following reasons:

First, carefully clean the carburetor, dredge all spray holes of the carburetor, and check whether the mixing ratio, oil level and oil needle scheduling of the carburetor are improperly adjusted, whether there is any problem with the air valve, whether the air diaphragm is damaged, whether the spring is broken, whether the throttle plunger is stuck and cannot be lifted, or whether the carburetor itself is aging and of poor quality.

Precautions:

Confirm that the carburetor has been cleaned and debugged, and then check whether the gasoline is deteriorated, whether the exhaust pipe of the air filter element is blocked, whether the air filter inlet is insufficient, whether the spark plug is defective, whether the high-voltage electricity is disconnected, whether the valve timing is wrong, whether the valve rocker arm and camshaft are worn, whether the valve is not tightly closed, and whether there is a problem with the valve spring. All these may also cause the general problem that the engine does not have high speed, so an independent investigation is needed.