First off I’d like to express my appreciation to all those in the community. I have a slew of cars and always the first thing I do is join the form to the corresponding vehicle. Recently picked up 1996 F150 4.9 pick up truck. I’m a big fan of excellent engineering. Thus I searched and finally found one after six months. My question is, I seem to have a fuel tank issue. I have done my reading and it’s very common for these older vehicles with the two gas tanks. One of the other fuel pumps aren’t working properly. That’s my question. Let me clarify. I have the two separate fuel tanks. The front one I believe is 18 gallons I guess that makes a difference and I do not have the reservoir canister tank selector type system. I have Read and Read on forms I can’t get a straight answer. My symptoms are my rear gas tank rough idle . My front gas tank works absolutely fine. Through the reading and videos on YouTube it seems that the rear gas tank pump may be bad. However, I also read that the front gas tank check valve system maybe stuck or broke because it is sending fuel to my rear gas tank. So is gas going in my rear gas tank because of my front pump or is it my rear pump checked valve isn’t working stoping return gas from the front pump?. I don’t understand why I can’t get a clear answer. My thought is if the rear gas tank check valve is broke, does the rear check stop the front pump gas operation return fuel from going to the rear tank or does the front pump stop the return gas going to the rear? So then the front pump when in use block the return fuel from going into the rear tank?or is the front pump check valve broke and sending gas to the rear tank? Richard