Another issue with my truck... No start

[MDpsd06]

Other day at work I went to start my truck and it would not turn over. It sounded like it wanted to but wouldn't. I returned the truck back to stock on my tuner and then the truck fired right up. I have had a long crank issue for awhile and just have not figured it out yet. I just did the HPOP STC update but I guess it wasn't that. I am starting to think it may be my lift pump? I have a airdog 2 165 and I am thinking the motor just may be going weak. I have changed fuel filter, and lift pump filters. What do you guys think? No codes in the truck.

 

[6.0 Tech]

When you say wouldnt turn over, are you talkng no crank or crank no star? It could be dummy tubes, stand pipes, or an injector o ring if its hi pressure related. You would need to air test it. I dont know why switching tunes would correct it though. Possibly a tune getting corrupted somehow?

 

[MDpsd06]

It cranks but does not start

 

[6.0 Tech]

Can you air test it?