Just a quick Q. If I connect the voltmeter wire of the SAFC on the positive wire of the fuel pump, I should get the reading on the voltage for the fuel pump only, right?
Its for a test and it seems the easiest way for a right away solution to have the reading while I drive the car.

Spec.

 

The only possible issue I see is that you'll be grounding at a different location than where the pump actually grounds. It may or may not cause a slight difference in the voltage measured.