Don't know.... Do You?

If its anything like the Western Stars that use the return valve then it won't have a crossover line and it won't equal the tanks out. Thats the whole point on the splitter valve to equally return the fuel to both tanks so you don't need the crossover line.

Like GP1500SC said the valve is only for return. The feed line with just be a straight t-fitting with one line from each tank going into one and then to the engine. If you have anything stuck in your fuel lines, return valve or the feed t block then it will either not be sucking fuel from each tank or its not returning to both tanks.