The easiest way to trouble shoot a fuel pump issue is:
- Confirm there is key on +12 volts at the trunk mounted IFS switch on both sides of the switch. Use a KNOWN good ground. Even better use a test light that "loads" the circuit.
- Use an ODB2 scanner to "ask" the PCM what it "thinks" the fuel pressure is.
The fuel pump should "prime" for about 3-5 seconds at EACH key on. The PCM will then shut the fuel pump off until the PCM detects that the motor is running.
NOTE, the fuel pressure must be maintained between cranks. So if the fuel pressure drops between cranks this is a problem.
Regarding how many volts at the fuel pump. That depends upon the way its measured. The Fuel pump driver module (FPDM) supplies a pulsed DC voltage. An advanced VOM that can read duty cycle is needed to correctly measure this. However IMO if the fuel pump primes at key on I wouldn't be as concerned about voltage.
IF this were my car I would be concerned about the fuel rail pressure sensor (FRPS) is sending a good signal. First the FRPS is a no start sensor. Next that IF the PCM is not getting a valid FRPS, that can explain WHY there isn't any fuel pressure. Given that the engine bay was wet perhaps that makes more sense than some other theories.
Also check the spark plug wells for moisture.
Other think to consider. When the fuel pump was replaced did you have to splice in the wiring? Sometimes if wired backwards the fuel pump will make noise but not build pressure.
Also people will forget to check the flexible fuel line inside the gas tank for leaks.