I have a 94 Dakota 3.9 and am pretty sure I have a bad fuel check valve. I just had a new fuel pump installed about four months ago so am not going to have the pump pulled again. I plan to install an inline check valve. Now I'm puzzled about the fuel lines. I have a service manual that states all models use a return system, then it says a separate return line is no longer used. How can fuel be returned without a separate return line? It can't go backward while it's going forward.