P-Pump 24V Won’t Hardly Start Anymore?

Hey all, been awhile since I’ve been on here. I did a p7100 conversion a few years ago and it’s been a great running, reliable truck. At the end of this summer it seemed to lose prime sometimes where it would take a few extra cranks to get started. As time has gone on it seems to occur more often and now it’s gotten really bad to where I can barely get it started and my whole shop is full of smoke from it sputtering around trying to get going. I’ve looked it over for fuel leaks and signs of the obvious but I’m not seeing anything alarming or different. Soon as it starts it runs beautifully as always. I’ve read some threads and gotten some ideas like maybe fuel line leaks or overflow valve possibly but does anyone have any idea where to start here? 2002 24v 215 pump fed by Raptor 150 that gives me consistent fuel pressure.

Check the fuel supply from the raptor into a bucket. Sounds like air to me. Probably has a crack in the return lines someplace that lets the fuel drain back while it sits.
Since it runs perfect once you get it running, I'd say the overflow valve is alright.

It might be worth mentioning I’ve had to turn the screw two or three times on the raptor pump the past couple years to keep idle pressure at 40. It would slowly drop over time but I thought maybe the spring in the raptor pump just got a little weaker year by year?

I would look at the pump? Is there a check valve or maybe the internal regulator is not sealing? Can you put a gage(vacuum capable) on the line and then shut it off and see what it does?

My 24 valve has a return line on back of the head. It got loose one time and cause a hard start. Do you mind if I ask you a couple questions about p pump swap?

Is it a oem overflow valve or tork tek valve with just a hole. I had a p pumped 24v in a 95 one time with the tork tek valve and if i parked up hill it would blead back for some reason, but if i turned key on and it run airdog for lile 10 seconds it fire right up. And ive had oem 12v trucks do this and doing the bic pen spring mod would straightened it right out.