It is a little frustrating to try and help someone that does not answer any question asked, it seems all you have done is search the internet for possible causes including civy engines that have completely different electronically controlled IPs
Copy that. I have, I’m getting good flow from the lift pump
. I’m starting to think more and more that this is a timing issue since I didn’t know about the witness marks, and just put the pump back on without adjusting it at all. Side question, would you recommend using thread tape on these? I have a lot of small leaks.
If it starts and runs it is not a timing issue, the timing could be off but that will not cause it to run then die.,
If you are positive you have good flow ALL the way to the IP then start looking at the return line, that is the only thing left that could possibly cause the kind of issues you have, if that checks out then you have a defective IP
ALL the IP needs is a good fuel supply, a good clear return line and return check valve, 24V to the shutdown solenoid and an engine to turn the IP that is all, if you have all of those things the IP is bad.
Since you have proven fuel flow the next step would be to pull the return line off the top of the IP and connect a hose to it going into a container so you can see if there is any fuel coming out of the return fitting.