Huh???? Is this the same guy who told you to find a code scanner for your Renix???
You need to tell him to stop trying to tell you things about your Jeep. Let him know you are going to ask us, cause we will give the right answer.
There is no way to measure your fuel pressure with a voltmeter, or an ohmmeter.. unless they are tied to a fuel pressure tester.
The Renix fuel pressure regulator only has a vacuum connection to it.
While you are testing the fuel pressure also do a flow rate test. This will give you an accurate picture of whether your fuel pump is getting the job done.
Autozone used to have fuel pressure gauges on their loan a tool program. Go in plop down a deposit and use it. Return it when you are done and get your money back