Float style carburettors, where to begin.

The float can stick, either letting no fuel (or not enough fuel) into the bowl, or not shutting off when the bowl is full, flooding fuel into the intake ports.

The jets can be blocked, not letting the correct amount of fuel into the engine, which can cause issues running entirely, or just when under certain levels of acceleration due to inaccurate fuel mixtures.

Also, but not specifically about float style carburettors, just carburettors in general.