How much fuel pressure are you running? How much is your injection system supposed to have? That is necessary information to solve this problem. Have you put a voltmeter on the wires going to your fuel pump? Have you contacted the manufacturer about this issue? Maybe about what are the "electrical specs" for this particular fuel pump... If all else checks out, and the wiring is good and getting the proper volts/amps, change the fuel pump because it must be internal. But the manufacturer will be able to tell you if it is or not.
Did the jeep come with the MPI? I am assuming by what you wrote, no. Let me know.
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