What is the reason for the humming of Camry fuel filler door engine?

There are several reasons for the humming of Camry fuel filler engine: 1, and the humming caused by excessive carbon deposition can be divided into excessive carbon deposition in engine, throttle valve and spark plug. Just go to the repair shop to clean it. 2. Hum caused by poor filtration: The most common thing is that the air filter is too dirty to go to the repair shop for cleaning or replacement. 3. Insufficient purity of gasoline: carbon deposits formed inside the machine, such as 90 # gasoline, are not as pure as 93 # gasoline. It can be completely replaced by high-grade gasoline. 4, spark plug aging: engine problems, cylinder problems, idle problems need to go to the repair shop for engine maintenance.