1994 f super duty 117000 miles 5 spd Driving to work other day truck starts to smoke heavily I checked oil pressure good Starts missing and pinging I towed truck in to my shop. When i get there, I could crank truck would run for 30 secs and starve for fuel. Finally would not crank at all I checked fuel cannister empty So i replaced mech fuel pump I started truck it smoked heavy diesel smoke it ran for 30 minutes The smoke never quit I cut it off I came back next day It started starving for fuel again when I cranked it. I put a 7 lb elec pump on frame rail no help. I have removed elec pump so back to factory fuel system. I cranked it today ran for 45 minutes smoked heavy I cut it off. I came back 30 minutes later crank it It ran for a minute starved for fuel . I can keep the truck running by bleeding the return lines from the head to the regulator But in another minute it starts starving again To keep it running I have to bleed it again. Fuel pressure at the shra valve jumps constantly from 30 to 40. I pulled the return line to the tank and the is no fuel Being returned. Any ideas ?
I was thinking bad fuel regulator or maybe bleeding injectors In the past six months I have replaced vc gaskets and one injector.

 

Welcome to Ford Truck Enthusiasts ash308

Have you tried switching tanks? Maybe you have a cracked pick-up tube or a plugged screen.

 

O ring leaking on injector It was letting comprerssion fill the fuel system holding the fuel out