Not be get off subject. But had a certified mechanic come in to work about a week ago and tell me that glow plugs for a cummins were 50 dollars each. And i just laughed so hard in my mind

It could be a overflow valve problem. how maybe miles are on the truck? Roughly a overflow valve should be replaced every 150K. Also did you check the fuel pressure before you replaced the lift pump?

 

im leaning towards the overflow bolt being bad. id change that and see how it does