I have been having a problem with rust above my rear tires. I have chrome fender flares, and the rust occurs right above them. I have repair it several time, but it keeps coming back. Can anyone give me advice on this?

 

Knowing what kind of truck you have and whether the flares are factory or aftermarket would really help us help you. Not knowing that, one common problem with fender flares or fender trim is having it move around relative to the fender / quarter panel. This abrades the paint and eventually leaves bare metal. Guess what comes next?

The other common problem with older Ford trucks is rust from the inside of the rear quarter panels above the wheel wells. You need to determine if the rust is surface or coming from the inside as your next step.