2000 Chevy C3500 with 5.7 (350)

I am going to run one of those fuel injector cleaners through the fuel line rail by the fuel injectors. I first must shut off the fuel pump to do this.

Is there a shut off switch or a fuse I can pull out to do this?
If so where is it at?

I have done this to both of my Fords and it made the vehicles run a lot better. Fixed the lean fuel mixture problem on my 99 ford windstar.

Thanks.

ECM-B fuse under the hood should do the trick

Which fuse it that?