I suspect your problem has nothing to do with the fuel tank unless your fuel line is sucking air at the connection. The 2007 vintage motorhomes do not have the OBDII system that gasoline cars have. Also the gas caps are vented but they only allow air into the tank. They do not allow air to escape the tank. As far as roll over valves in the vent hose (which I doubt), if the motorhome gets upside down the fuel will be running out of the filler tubes which are much larger than the vents. I am sure all Country Coaches are not the same but in our 2007 the vent hoses leaves the top of the fuel tank and runs over to the filler tubes just inside the fuel cap and connects there. You can see it if you remove the cap and look just inside the tube on top.
Has the lift pump been checked? Every time you turn the ignition switch to run, the lift pump will run for about 30 seconds. Easy to hear if the engine is not running.
Have the fuel and fuel/water separator filters been replaced? Common problem.
I remember hearing of the same problem a while back and they could not find what was causing it. It turned out to be the mount for the fuel filter had a very small crack in it which was allowing air to be drawn into the fuel system. Very difficult to see and with the air in the system the fuel pump could not bring the pressure up to where it should be.
Just some thoughts,
07 Inspire 52059
Originally Posted by smlranger
Well according to CC, I do have rollover valves on the fuel tank vents. However, they say issues with some valves were in earlier model years....2002-2003.
I'd rather be beat with a big stick than to have to take the bedroom apart again so Cummins can access the top of the engine, but I guess if I am going to find the issue for the fuel delivery problem, I'm going to have to take the coach back there.
At this point, I'm missing my old CAT 3126E which was never in the shop for anything other than routine maintenance in 8 years of ownership.