2011 Peterbilt 389 fuel won’t stay equal

[Ben50291]

no sir. I pulled it out. I had to drain the coolant cuz i have the fuel tank heaters and I inspected it for cracks and I blew through it, then plugged it with my finger and blew through again without escape. I would think the issue has to be from the fuel splitter back to the tank because it's running off driver side tank and I would think if it was an issue from the splitter up to motor than it wouldn't run? I have put a valve on top of passenger side return line because it had drawing from drivers side and dumping it into passenger side. I have since closed it once it stopped drawing off passenger side. I may have to install a crossover line between the tanks but I was hoping not to. I do have ports on the bottom of tanks. They are a 3/8 inch plug. Is there fuel line available in that size? Is there a special "goop" to put around elbow fitting so that fuel wouldn't leak out around it.