As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
UPON LEAVING KGMU, WE NOTICED LOUDER THAN USUAL CABIN NOISE ON TAKE-OFF. UPON QUICK INSPECTION WE REALIZED THAT CABIN PRESSURE WAS EQUAL TO OUTSIDE ALTITUDE AND WE HAD 0.0 PSI DELTA P. WE LEVELED OFF TO CONFIRM CABIN ISSUES AND REQUESTED A HOLD BURN DOWN TO BELOW MAX LANDING WEIGHT AND PROCEEDED TO DIVERT TO KGSP. PLANE/CREW AND PASSENGERS ALL SAFE AND WELL.