I am guessing that you do not plan to run the windstar engine while you are running the carpet machine.
The fuel pump on the windstar only runs when the ignition is ON.
I would be uncomfortable with running the high pressure fuel into the passenger compartment of the windstar.
I am guessing that your "older van" had a mechanical fuel pump on the engine? If so, the line that you put the "T" into and ran into the carpet machine engine was under no pressure.
Taking that into consideration, you will need to be very careful trying to use a high pressure fuel system. That would require that all the fuel lines be up to the high pressure, most likely, you would start by replacing all the fuel hose that would be in the high pressure path.