Old Jetta feels air leakage when refueling with load.

I want to ask why the old Jetta feels air leakage when refueling with load. The fuel injector is blocked, and the air intake is too large. According to official website, an auto expert. Old Jetta felt air leakage because the fuel injector was blocked, the air intake was too large, the exhaust pipe leaked, the exhaust valve cover of the oil-gas separator was soft and aging, and it cracked and leaked. Jetta, once a model of Volkswagen brand, was first marketed in Europe in 1979, and the first domestic Jetta A2 was assembled off the assembly line in FAW-Volkswagen Car Factory in 199 1.