I've recently noticed an electrical buzzing that has gotten progressively louder in my 1990 C4. It seems to loudest in the vicinity of the fuel sending unit, near the relay box. I know its not the brake system pump. I thought it might be the fuel pump, but I had never heard it so loud before. Also, it doesn't run when key is on with the engine not started. Only with engine running. I would think the fuel pump would run with the key on. I disconnected the sending unit, but buzz persists. Any ideas??
Just trying to nip it in the bud, thanks for help,
Dan