Hey GP! Question. Does the LED/lights on the FM radio go dim/out or just the sound go out/static?
If the lights/leds go out, it’s a wiring issue. Your radio is drawing the power from the battery and there isn’t enough left over to run the radio. This happens to me when my battery is low on charge. (might want to check the water in your battery…) Does your FM go out when you start your motor? Did this just start all of a sudden?
If you get static/lose of sound than it’s an interferance issue. Follow Derek’s instructions for that.
How’s that for 20 questions?