Originally Posted by RonMaiden
Clean it often and you won't get buildup. Dirt isn't going to get into the tank so keeping the outside clean is the best thing to do.
It was a dry year in the midwest, so the dust was worse than normal.
This pic was taken a few hours after washing and drying the car in town, I drove on one mile of gravel roads to get this dust accumulation. After 200 miles, it was like an archeology site digging out the fuel cap from under the accumulated dust and dirt buildup.
I don;t have this issue at home, we don't have gravel roads in L.A.