Installed am fm stereo and getting a popping noise when motor is running

[gwgautney]

I recently installed an am fm stereo in my boat and I ran it to its own battery that is not tied in to anything on the outboard yet when I crank the motor I get a continuos popping noise through the speakers. It plays fine with motor off. Any ideas. the wiring is zip tied together with all of the other wiring it just doesn't connect to same fuse block or battery.. has me puzzled

 

[UncleWillie]

Re: Installed am fm stereo and getting a popping noise when motor is running

By "Popping", I assume you mean that you are hearing the spark-plugs firing in the background of the Radio.
The Noise speeds up when you Rev the engine.

Does the radio's battery share anything with the Engine Battery? Battery Switch? Battery Charger? Ground Connection? Anything at all?
When you separate the wiring does the noise diminish?
If you tie the Batteries Grounds together does the noise diminish?