1993 Ford Ranger cranks stongly, won't start

Hi. Ranger will not start. With the key on, fuel pump continues to run, producing 40psi. I tested for spark on one plug, spark is present with plug grounded against engine exterior. Normally, when the key is on, the fuel pump would run for a moment and turn off. When the engine was cranked as such, the truck started immediately. When the fuel pump runs continuously, with the key in on position, the engine will not start when the key is moved to start location. One time, when the engine happened to start, I drove it for a few miles, came home and tried the diagnostic codes. It provided 33 code only. It seems the diagnostic system will not start as long as the fuel pump continues to run. I have found the symptoms described in various forums but I have not found a solution. I have replaced the fuel filter (first), the fuel pump twice, the engine coolant sensor, the fuel pressure regulator, rotor, cap, wires. There were times over several weeks when, with the key on, I could pull EEC relay and fuel pump relay, shuffle them about in various sequences, then the eec would be energized, the fuel pump relay energized, then the fuel pump would stop. The engine would start. That type of maneuver no longer starts the engine. What can be done? Thank you and bless you.