36 is almost always a fuel delivery problem. You can take a couple of steps to troubleshoot.
1) Pull the fuel line loose from the carburetor and aim it into a quart sized fuel proof container of some sort. Push and hold STOP for 30 seconds. You should be able to obtain at least a pint of fuel in that period of time. If not, remove the fuel filter located just in front of the fuel pump and try again. You may have a plugged filter or a failing fuel pump - this test will help determine that.
2) Ensure the 2 carburetor mounting bolts (10mm) are tight (30 in-lbs). Listen for any whistling noises due to a vacuum leak in and or around the carburetor and intake manifold. You can use any non-flammable spray such as Windex to spray around the gaskets on the intake and carb while it's attempting to run to see if the engine speed changes drastically or if the engine even attempts to run better
3) The carburetor used on the HGJAB series are all CARB compliant for California standards and cannot be rebuilt, nor contain any running mixture adjustments. They are prone to varnishing due to the newer fuel blends if they sit for any extended period of time. This can happen in a matter of a few months in many cases. Some people have had success in disassembling the carbs, soaking them in solvent and re-assembling. I have had minimal luck in trying to do so. If everything else above has been checked then it's time for a new carb.
94-Newmar Kountry Star 40-KSDP
Spartan/Cummins 8.3C-300HP/Allison 3060 WTEC-II/25yr RV Tech RVIA Certified/Onan-Cummins Certified