Fuel Pressure Regulator or Fuel Pump?

Hello!

I have a 1994 Chevy S10 Blazer Tahoe. 4.3L V6 Manual.

After sitting overnight it requires a lot of cranking to start up. To the point where the battery starts to die, needs to be recharged, and cranked again for A WHILE until it actually starts.

So, IT DOES start, and after driving for a while, it will start up without problem for the rest of the day. But ultimately, it will sit overnight, and have the same problem the following morning.

Is it possible to tell if the issue is either the fuel pump or the fuel pressure regulator?

It's fine if I have to change both, but would rather avoid it if anyone out there knows how to tell.

Thanks!