Truck Repair: fuel restriction, path of least resistance, suction lines

Question
hello! i replaced a return flow splitter but my fuel tank on the left keeps flowing to my right tank leaving my tank on the left dry cutting the engine off, ok i let it set for a while and the fuel some of it flows back to the left tank. this only happen when im driving not idling i need to know what causes this it just start happening

Answer
You should have dual returns & suction lines.Fuel like anything else will take the path of least resistance.It could not be pulling fuel from the right tank & just returning into it.First make sure they look like they are returning the same amount of fuel into each tank.Then look for possible suction line on the right tank collapsed or restricted.