When the Fuel Pump pumps fuel to the engine, does any fuel go backward, or does the sending unit stop it. I don't think there is a little check valve in there. So does fuel go backward at all?
No. The pump is below the level of the pickup so any fuel in the lines from the tank to the pump would tend to stay there. Assuming the tank vent is open and working properly, even the heating and cooling of the tank would not cause fuel to be pulled in or out.
Thanks Dana. I'm just wondering because I replaced my fuel tank, and there was rust in the line, so just wanted to make sure nothing flows backward at all after running the engine. I'm also replacing the fuel line tank to engine