Yep I'll get you some pictures tomorrow after I pull the cab and before I pull the tanks.

 

https://www.ford-trucks.com/forums/8...r-valve-3.html

Check this link

On the valve you should have:
2 lines from rear tank
2 lines from front tank
2 lines that run towards the engine


Something like this:

 

way to go bro, awesome pic. Now where the heck is that!?!? hahaha

 

If I told you what would you need me for?

Nah it's the diagrahm that comes with the aftermarket switch.

 

on the truck, where is it on the truck? hahaha

 

Driverside frame rail near the back of the cab. It may be grey or black in color with all the lines.

 

Sounds like the switch is defective and alowing making selector valve open to both tanks and you are sucking air from the bad tank when the switch is un hooked the valve will stay on witch ever tank it was on so I think that could be whats going on, the electric pump wont overfule it because the IP regulates the amount of fule and returns the excess.

 

Okie dokie! So i unplugged and i made it about 30 miles before it died. Unplugging it is killing the electric fuel pump apparently because one of my lines from the fuel filter head to the IP is clear so i could see it was dry, mostly. I hooked it back up and kaboom it started right back up with the extra rattle and noise. I guess the IP had just enough draw to feed the engine but when it created a vacuum on the tank, it killed it. I took the cap off and it sounded like i took off the top to a soda but it was vacuum. I scoured the frame rails and all over and i see no fuel selector valve. I am not sure what the hell is going on. I am going to crimp and close off all lines to the rear tank and see what happens then with the noise, i sealed off the line in the engine compartment with a zip tie and silicone so air isnt coming in that way. I am afraid it will send fuel to the rear tank somehow if i unplug it again. I am going to get a jumper wire and test which wire does what on this plug that is on the back of the selector switch. By going from wire to wire i may be able to isolate each item, pump, gauge etc etc. Thoughts on wire colors and where they go??? Thanks fellas.

Yeah its crazy, I know! - The Truck

From top right going clockwise:

Green with white stripe, large
red with yellow stripe, large
solid red, large
blue with yellow stripe, small
yellow with white stripe, small
yellow with blue stripe, small

 

That is a crazy way to wire a fuel pump.
What kind of pump is it you may need a regulator.

 

wreckinball how about a pic of the fuel pump and the wiring to it, can you post some?
I have a hunch this sucker is either wired totally wrong or is the old style that needed a regulator.

 

Wreckinball here is a pic of the top of the front tank hookups. the little hose on top is the vent line, it clips to a crossmember on the bed, and if it is working you should have no vacumn on your tank.

 

The line from the top of the motor down to the frame, is the return and goes to the fuel selector valve. If you look towards the left shock tower there are two lines sticking straight up, these are the fueline going to and from the water seperator, which you wont have so yours should be tied together there.

 

that would be the f150 fuel switch in the cab since it had two tanks as well.

 

i havent found it yet, i will check tomorrow to confirm if it is in the tank. i may need to pull the bed off and get this sorted, how hard is that? i have a way to hoist it, i just need to know how hard it will be to remove.

 

There is the selector valve mounted to the frame right behind the corner of the tank.
I removed the valve and all lines together in one piece still together, but didn't think about taking a picture. I will in the morning and it will show the position of all the lines.