I have an old fg monster with leaky fuel lines. It has a soft black tube witch seems to be the inlet tube (connects to the bottom of the carb) and a harder yellow one that is the overflow tube (connected next to primer bulb) . This seems completely counterintuitive for me. Is there something I'm missing? And all the pictures of the Modell have the same setup. And can I use the same hard tubing for both of them, or is there a purpose with a soft inlet tube?