Recently I have been getting a lot of static on my radio when I have it on AM, so much so that it is impossible to hear anything but the static. It only is a problem when the engine is running, with the engine off, it is clear of static. FM is fine. I haven't done anything to the engine electrical system and the antenna seams fine. The radio has always worked fine in the past. Anyone know what I should be looking for, possibly something on the engine? Thanks. Frank