when you attempt to start the truck, try hooking a 3rd, good battery (so voltage wont drop during cranking) to the fuel cutoff solenoid, maybe its not liking the voltage drop during cranking.

with third battery/ jumpers, hook negative jumper to negative battery cable. then unplug the fuel cutoff connector and instead put the positive jumper on the solenoid, it should click, try cranking/starting.

Good Luck