None.... Fuel pressure does not figure in whether the pump runs or not. That is the job of the regulator, and it controls that by how much fuel is returned to the tank with the fuel pump constantly running. It either has to be the relay sticking, the oil pressure switch, or the driver in the ECM sticking. If you have AC switch the two relays ( they are side by side behind the driver on the fire wall) chances are both are not bad.
LS1 v8 T-Top 87 GT