What are the symptoms of a faulty intake manifold check valve in the Excelle?

[DeAdam]

The symptoms of a faulty check valve in the Excelle are increased air flow velocity at the carburetor throat, increased fuel discharge from the injector, and consequently higher fuel consumption. For carburetor or throttle body fuel injection engines: the intake manifold refers to the intake piping from the carburetor or throttle body to the cylinder head intake ports. Its function is to distribute the air-fuel mixture from the carburetor or throttle body to each cylinder's intake port. For port fuel injection engines or diesel engines: the intake manifold only distributes clean air to each cylinder's intake port. The intake manifold must distribute the air-fuel mixture or clean air as evenly as possible to each cylinder, so the length of the gas flow channels in the intake manifold should be as equal as possible. To reduce gas flow resistance and improve intake capacity, the inner walls of the intake manifold should be smooth.