I will need the model number. There are 17 different specifications of the 4KY units.
It does sound like you are having a fuel pump issue, and a code 36 is almost always fuel related.
Lets test the fuel pump.
To do the test, remove the fuel line from the carburetor. It will be necessary to cut the crimp-type hose clamp.
Place the fuel line in and empty container.
Press and hold the 'STOP/PRIME' button for about 10 seconds.
When you first press the button, there will be a 3 second delay before the fuel pump activates.
When the fuel pump does activate, it should make a faint 'humming' sound. It should not make a loud 'clacking' sound. A loud 'clacking' sound indicates that there is air in the pump, and can indicate either a faulty pump, or no/not enough fuel getting to the pump.
There should be an immediate strong, steady flow of fuel in a pulsing flow.
If there is no fuel flow, or if the flow seems very weak and thready, locate the fuel supply line.
The supply line is attached to the left side of the set, about midway between front and back.
If you look down the left side of the set, you will see a large black ground cable, then a gray conduit (this conduit is the AC output wires), and then the fuel line.
The fuel line attaches to the fuel filter, and the fuel filter is screwed directly into the pump, which is located inside the set, all the way to the left.
Remove the supply line from the filter, and attach a length of fuel hose to the filter.
Place the end of the hose into a gas can.
Now press and hold the 'STOP/PRIME' button again, for about 10 seconds.
If you still do not get sufficient fuel flow, the pump is bad and needs to be replaced.
If you now get good fuel flow, but did not on the first test, either your coach is low on gas (there must be at least 1/4 tank for the set to run), or the fuel lines between the tank and genset are bad.
If you have an older version of this genset, it will not have the prime function, and you will need to actually crank the set to check for fuel flow.