Does a 2018 5.0 have a Schrader valve to check the PSI on the fuel? If so where is it, and if not how do you check it?

 

No valve on my 5L, but check it with my hand Scanner.
Cold key on before cranking is in the 60 psi range.
After starting the high pressure pump rises it to anywhere between 2000 and 3000 psi as it needs.
You may begin detecting some delay in firing while cold cranking when the ambient temp gets below about 45*.
Good luck.