I changed my brass float today, when I took the old one out it seemed clean enough but after I had put the new one back in, I noticed the old one had dried with a rust looking type oxide on it and it was powdery, is this normal for gas to do brass like that ? , or do you think I may have rust in my tank as I have the carb off being rebuilt and I am thinking if I have a bad tank it may have led to my carb problem.Appreciate your guys input.