How to check fuel pressure?

You normally need to use an adapter fitting that connects between the fuel line and the fuel rail. Then your gauge connects to that adapter. First thing though is to drain off any pressure, to do that you normally would just remove the pump fuse and try starting the car a few times. However Dodge didn't use an individual fuse on that car only the relay that is built into the TIPM. So to release the fuel pressure you need to remove the rear seat lower cushion, then the access cover for the fuel pump. Now you can remove the electrical connector for the pump and try starting the engine a few times. When it no longer tries to start the fuel pressure is low enough that you can remove the fuel line, and as you are checking the pump pressure you can do that right there as well using the same adapter you needed under the hood. The normal pressure with the key on engine off is 53-63 PSI.

https://www.2carpros.com/articles/how-to-check-fuel-system-pressure-and-regulator