Help! Truck won’t start!

[JMBT]

Agreed with Rawze on the ABS not being the culprit. Maybe the voltage change when you unplugged with the key on popped a fuse somewhere?? It shouldn’t have but who knows. Reaching in the dark here, but I would check all your fuses and relays related to the ign and ECM. If a 2250 or 2350, does the injector harness have a fuse? Rawze may know. I know when we need to crank the engine without it starting we unplug the injector harness where it goes into the side of the head just below the rocker cover. (2250). Maybe check there too. Does the lift pump have a fused link?? Can you hear if running when you turn on the key? If not maybe you lost your prime. Just bouncing ideas here. Would be curious to know what it was when you figure it out, please report back. Thanks