Just got a 1991 e250, dual tank. When driving on the road it started acting like it was running out of fuel. Later when starting it may start or not, if it started would only run maybe 1 min. During that time if the fuel peddle was pressed it might reb up or run ruff then stop. Then it may start or not. Found that there was not enought pressure, replaced HP pump with now go one. Still acted about the same. Nexted tapped on the fuel slector valve and it started and was driven about 5 miles. During that time it was driven hard to see if it was going to make the trip back to my home town. But in the last mile it acted up again just like before.
By the way one tank doesn't show a fuel level and the van sat for a while, but was cranked and driven around the yard every few weeks for a short time.
I said all this to ask:
Can the fuel slector valve cause a pressure drop?
If I disconnect the HP pump should I hear the tank pump run?
Is there a test plug to read voltage at the tank to make sure that there is constant power to the pump?
If no test plug do you know the coler code so I can tell witch wires go the the pump?
Thanks

 

Welcome to FTE!
Having sat for an extended period of time, the fuel may have varnished in the selector valve, partially plugging it. Have you checked the fuel pressure yet, or tried to switch tanks?

 

There was very little fuel in the tank, not enought to show on the gauge. After the test drive of a mile and with it running ruff the last part of the drive I thought it was about out of fuel so I hurried back. Later I felled both tanks, one tank reads ok but the other one doesn't read. When running switching tanks doesn't seem to make any differance.

 

Oh The fuel pressure seems to come and go. By disconnecting the fuel line and running the pumps,the stream of fuel varies. Also I removed the slector bowl and the fuel looked ok, but not sure how the slector works ? understand that the pump pressure from the running tank switches or controlls the slector.

 

If it is sticking, it will pump fuel from one tank to the other and have little or no fuel pressure to the engine. I had to buy one for my Dad's 89 F150 about a month ago. The Ford dealer was the only place that I could find one. Even NAPA said that there were no aftermarket Ford valves. It was about $90.
You should be able to hear the tank pump running with the frame tank unplugged. It will only run for about 2 sec when you turn the key on.

 

Thanks for the info. I couldn't hear the tank pump running so, Today I temped in a good tank with pump. First I removed the rear tank lines from the slector valve and installed the new temp tank lines ran the pump. Nothing came out of the slector valve, so I ran the input line to the HP pump and put the return line to the slector valve. This worked very well, drove the van 60 miles with no problem. But I did hear a new sound? seemed to come from the motor, this sound would start when in drive and pressing the gas pedal, when I let off the pedal no sound. If I was in park and pressed the pedal there was no sound.? another mystery?