1989 F150 8cyl not getting fuel to engine. Checked relays, replaced fuel filter, checked inertia switch and replaced tank transfer switch. Disconnected fuel line from tanks and put fuel line in a spare tank. Inline fuel pump will pump fuel and truck will start. When connect back to tanks truck will run briefly and then die.
Unlikely both in tank pumps have died. Any other suggestions?

 

Here's the schematic for the fuel pumps.

If you have 12 volts to the pumps, disconnect the larger hose coming from each tank and going to the back of the transfer valve. When you crank the engine fuel should be pumped out of the selected tank. If no fuel comes out of the hose the pump is bad.

The reason why the engine ran a couple of seconds after you did your test with the spare tank is because of the fuel that was left in the transfer switch reservoir.