The fuel bleeds down when the engine is turned off. From the supply line i have a clear plastic filter before the fuel pump A glass fuel pump and a small glass filter up top by the carb. While the motor is running there is air in the fuel pump bowl and the filter up top is not full. The truck runs good down the road and ideling. When i shut it off the fuel bleeds out of the top filter and the filter before the fuel pump the glass dome on the fuel pump is not quite full. I have to crank the truck with the choke closed for a few seconds then push tit in and step on the gas. It is 6 volt so this takes a lot of juice. 216 51 chev 3100. why does it bleed back? Thanks