If I leave my TR6 for a week or two without running, it is very hard to start. I am noticing that the fuel filter is just about empty after this time. Priming the pump with the little lever on the bottom of the pump does not seem to do much if anything to fill the filter. Is the fuel somehow siphoning back into the tank or would there be that much evaporation in that time. The engine is definitely struggling for fuel on startup. Is there a built in back flow valve in the fuel pump or would this be a needed addition to the fuel line?