I just rebuilt my carbs & I want to fill the carbs to make sure they are not leaking etc. I have not put the air cleaner lower section on yet. Anyway, I turned the key on & the fuel pump runs for about 2 seconds & shuts off, no fuel thru the fuel filter. I'm thinking that since I don't have vacumn on the auto fuel shut off valve on top of the tank that may be my problem. I was thinking about hooking my mighty vac up to the line & giving it some vacumn. Should this work or is there something else I need to do before the fuel gets to the carbs?