Thanks for the reply. I was tryin to get by cheap since i really need to replace rear tank. Maybe i can plug the return line somehow just for the time being until i can get a new tank and pump. Thanks Again
Sean

 

You may also have a high pressure check valve in the rear tank and plugging the return line only may not help.
You either need to replace the rear tank (for the leak) and the fuel module (some say pump) or plug both the supply line from the rear tank and the return line to the rear tank.
With the front tank selected at the dash there is no power going to the rear tank anyway.

 

Do not try to disable the tank, if you do short of plugging the line to the rear tank you will still have the same issue and no way to switch to that tank to empty it (use the fuel in it). Here is the recall kit for the issue, I ordered it and installed it on my 95 f150, it should cure your issue.
1L3Z-9J274-AA
The kit comes with two, be careful people are selling them as singles sometimes instead of pairs, it costs around 200.00, good luck.

 

I found the part at my local Ford shop. I don't know if it's for one or for two. You would need to call them to confirm. FWIW this shop sells at wholesale via the Internet and at retail over the counter. If you buy from them OTC just ask for the internet price and they'll give it to you.

 

Is this part 1L3Z-9J274-AA only for f150? I noticed my 93 f250 7.5l is starting to send fuel from the back tank to the front tank.