cummins fuel filters change out

I can only give you information based on my 07 ISB in an 08 HR. First determine if your secondary/chassis filter has a priming pump on it. If it does replace the filter, cycle the key a few times and then pump the primer knob until you feel the system pressure build up. Fire the RV up and set the fast idle, see owner's manual. Let the vehicle run for a bit. At one point you will feel it stumble as any air in the system passes through the injectors. When the engine smooths out disengage the fast idle and shut the engine off. Remove your engine cover in the bedroom, locate the primary fuel filter which is on the engine and replace the filter. Cycle the key a few times then head back down to the secondary filter and pump the primer until you feel the pressure build up in the system. Repeat the start up procedure used for the secondary filter.
If you replace both filters simultaneously you will have start up issues.
Randy