Speakers in 99 ford ranger popping?

[fireman32]

My oldest has inherited this truck and we’ve been tinkering with it for awhile. The question is while the ignition is on, the speakers sound perfect, if the engine is running they pop like a static drum. I’ve cleaned 10 ground wires and even reground the radio itself with no improvement. Could it be the alternator going bad and causing feedback through the speakers? There is no whine or whistling Through the speakers while accelerating, which is why I’m not sure it’s the alternator. I’m not sure what other gremlin it could it be. 4 factory speakers and the factory radio. He plans to replace the radio, but I’d like the speaker situation fixed first.

 

[Cmp1]

You can get one of those interference isolaters pretty cheap,,,,I'd try that,,,,could be the coil,,,,

 

[Cmp1]

Connections all good?

 

[fireman32]

I read a little about the isolators I may try that. And yes all the connections seem good.

 

[Cmp1]

It's usally something simple,,,,