The normal mode of operation of the fuel system is to bleed off pressure after a period of non-use. However, at time of hitting the key to <ON>, the pump will pressurize the system and, it will drop two or more lbs when <OFF> and hold that pressure for a given amount of time while, over longer periods of time of non-use, it will drop to zero psi.
After pressurizing the system, if one were to open the pressure relief valve on the fuel rail (Schrader valve), normal event is to expel gas under pressure. If this is not happening- the pump is not working and should be replaced.
You can check for leaks in the following flow:
-there's a quick disconnect at the pump that attaches to the fuel supply line.
- this line runs along the frame and terminates with another quick disconnect, male end.
- this end mates to a female quick disconnect that is part of the SS braided flex line, just ahead of the frame rail
- from there this flex line goes up into the engine bay terminated with a quick disconnect fitting which mates to the fuel rail inlet.
IF there's a leak, you will find it at any of those points in the above flow. As DHV stated, clearly you would smell it and see it.