starts then dies, try it next day, starts and runs. on 1998 GMC 3500 Pickup

I've been un-hooking batt. between try's.Has two tank's, how do the fuel pump's work with each tank? What about the transfer pump?

Asked by for the 1998 GMC 3500 Pickup
there is a transfer pump and a transfer pump that is controlled by module. this can be hard to diag, seek est and