RV motor won't stay running

On my rigs past, there was a fuel filter located inside the frame rail on the drivers side. You need a special little tool to unlock the tabs. All the auto parts stores sell them. There is also a filter sock located on the in tank pump that could be clogged also. You can test the fuel pressure at the fuel injector rail. But I would put a new fuel filter on it first, and if no good, then test for pressure, if still no good you might need a new in tank fuel pump. Have someone turn the key to on while you listen down at the tank, you should here the pump hum, if not that may be your culprit.