I have a 95 f150 with dual tanks. Back tank has never worked since I've owned it. The fuel pump in the front one went the other day, and while loosening the straps gas started dripping, tanks rusted to beat hell. Dropped the rear gas tank, pretty rused, no holes yet, and the old gas smell would about kill you.I got a new front tank and pump, ($340....DoH), put it in and decided to leave the back tank out untill I can afford to replace it and the pump, (like $360...double DoH). Started it up, was running fine, looked underneath and gas was dumping out of the rear return line. I should have known there was a check valve in the pump.
My questions are, how much pressure is on the return line? and could I cut the line from the sending unit, plug it into the disconnect and use the old rubber hose, bolt and couple of clamps trick to get me going for awhile?

 

From what I thought, there is next to no pressure in the return line, but you tell me. Was the gas just dribbling out, or was it really squirting? It's just to guard against over-pressurizing the system, so at idle or lower speeds when the pump is pumping more gas than being used, the excess returns to the tank. At higher speeds little or nothing will come out of the return line.

I dunno about just plugging the line up with the "bolt and clamps". Jacking around with the fuel system just to "get going" is never a very smart idea, and could lead to over-pressurization, which could blow other old hoses and in general screw things up all over the place. If anything, I would merge the rear return line into the front one, so at least you're not plugging the system or leaking gas all over the place.

 

Here is a diagram of your fuel system and as you can see the return line goes to both tanks and there is a check valve for the pressure line and a shuttle valve for the return line in each tank.
The pressure line could have up to 95 psi on it but runs at about 32-42 psi running and 45psi not running if pin #6 of the test connector is grounded for a V8. An I-6 is around 55 psi.
The return line is the fuel that is return to the tank to keep it from vapor locking and to maintain the fuel pressure at the fuel rail by the fuel pressure regulator.
As you can see the pressure in this line will very and should be less than 55 psi.

If you can block (plug) both lines to one tank than you would have the same as the one tank system and you should not have any higher pressures on the hoes than you had before with two tanks.

Fuel system:
http://i54.photobucket.com/albums/g9...FielSystem.jpg

Fuel Pump:
http://i54.photobucket.com/albums/g9...yAssembly2.gif

Fuel pressure regulator:
http://i54.photobucket.com/albums/g9...Fuel/fpr02.gif

Test Connector:
http://i54.photobucket.com/albums/g9...taLinkConn.jpg