just something to think about. I had a similar issue, and in the end it was 2 things. My fuel pump crapped out, bought a new one and almost immediately had issues. As long as the truck was running, the fuel being pushed thru would keep the pump cool enough to run. As soon as I shut the truck off the pump wouldn't work. I would have to wait for it to cool down, and pressure would slowly return.
After dropping the tank about a half dozen times, to figure this out, I no longer had problems with the pump. Now I had random loss of power to the pump. In the end it was the wires on the sending unit where they enter the tank. Everything looked fine, but hitting a bump, or just general vibration would cause the wires to move just enough to break contact. Once I replaced the sending unit too, all my fuel issues went the way of the dodo.
Kind of a long winded post, but maybe it can help with troubleshooting this.
Oh yea, when playing with the sending unit and pump, you need a friend to keep turning the key to the run position, so you can use a multimeter at the tank checking for power. Be extremely careful though. When my sending unit finally kicked the pump on (sending unit and pump were removed from the tank, but wiring was connected), it dumped the fuel in the pump, and the loose wiring caused a spark...the X lived. Have a fire extinguisher handy.
is there a way to bleed them if there is air trapped in them. i removed my fuel rail and injectors for my cylinder head fix.
There really shouldn't be air trapped in the system. Kind of like running out of gas. Add fuel, and the system should purge on it's own.
