2004 Ford Explorer fuel pump and fuel filter changed

Check fuel pressure and fuel pressure regulater

Fuel Pressure Regulator
The fuel pressure regulator (Fig. 79 ) is attached to the fuel rail downstream of the fuel injectors. It regulates fuel pressure supplied to the fuel injectors. The regulator is a diaphragm-operated relief valve. One side of the diaphragm senses fuel pressure and the other side is connected to the intake manifold vacuum. Fuel pressure is established by a spring preload applied to the diaphragm. Balancing one side of the diaphragm with manifold vacuum maintains a constant fuel pressure drop across the fuel injectors. Fuel pressure is high when engine vacuum is low. Excess fuel is bypassed through the fuel pressure regulator and returned through the fuel return line to the fuel tank.
Fig. 79: Identifying Fuel Pressure Regulator
Courtesy of FORD MOTOR CO.