I have a 1991 Ford E350 Econoline XLT van with a 5.8L engine,fuel injected. It has dual tanks from the factory and alsoa dash mounted toggle switch from the factory. After buying it a couple of weeks ago I went to put gas in both tanks the back one was half full but the front was completly full. This van had been sitting in storage for more than 2 years not being drove so I bought one of those gas additives for both tanks seeing as how the gas was so old. I started out driving on the main back tank and then one day tried using the front aux. tank. I went maybe 12 miles and it died. I had to switch back to the main tank to get it to start. So I figured it was probably the old gas in the tank that was full. But, the next week I had started it up in the drive and switched tanks again and it ran great on the tank that it would not run on before. The next day Igo outto start it up and itwon't till I switch it back to the main tank. But the third morning I attemp to start it from the main tank and it will not start from it either. Three more days went by with me going out and trying to start it on both tanks each time. Nothing !!! I came back on the fourth day and it fired right up ???? I switched it back and forth several times with it running up to 5 minutes between each time and it ran fine on both tanks. So, I figure itis the fuel selector module or what ever it should be called. Butall I have on this vanfrom the (gas tanks towhere they go into the fuel rail and the pressure regulator), is the "fuel filter, high pressure fuel pump and what Ithink would be what swithes the tanks, what I'm calling a fuel selector. It has four lines going into it,"2 from each tank" and then 2 coming out of it. One of the two goes into the fuel pump, the other goes on up to the top of the motor. This is a factory partand there are no wires going to this thing. I talked to 2 autoparts dealers in town and they said no way. What they showed me looked nothing like what I have and theirs had a place for a large electrical plug in.Can this thing be running / switching from vaccum or pressure somehow and at times maybe getting hung in between and cutting all gas flow off??? Help !!!!!![:@][:@][:@]

 

I'm having similar problems with my'91 E350,an have changed out the fuel pump/sender assembly in one tank.The part you're speaking of diverts fuel when switching from one tank to the other..usually is'nt troublesome.

 

The part your refering to does not really switch tanks. It is really nothing more than a valve that operates from the pressure from the tank mounted fuel pumps. Basically, it keeps one tank from filling the other. Thats what mine did when the valve stuck halfway thru switching.There are no wires or vacume valves. I did away with all the fuel injection and changed over to a carb. Mounted two electric fuel pumps, one for each tank.