If you look at regulator specs you will see that they keep pressure to a certain level, set or adjustable depending on the regulator, AND they limit flow. Most of the cheap ones have very low flow while the more top of the line models limit pressure AND allow higher flow. You might have reduced pressure and flow limit from your regulator.
2006 GMC 2500HD CCSB 4x4 Duramax/Allison, Titan 52 gallon fuel tank, Prodigy Controller, B&W Companion Hitch
2010 Jayco Designer 35RLTS, Cummins/Onan RV QG 5500 EVAP, Progressive Industries EMS-PT50C, TST Systems 507 TPMS, RV Flex Armor Roof