C15 starting issues.

Update- i took the filter housing completely apart, cleaned and inspected everything and put an oring on the end of the bleeder screw. I was getting better fuel pressure but only running about 65-75 at idle. I put clear hoses inline to make sure I wasn’t sucking air and getting adequate fuel to the transfer pump, nothing changed.
I put a new transfer pump and now I’m getting around 70 psi while starting but it will not be crank. I can spray the slightest amount of ether and it fires right up, it doesn’t smoke or anything. With the new pump I’m getting around 90 psi but it is very sporadic my fuel gauge needle is jumping like crazy. (Did this with old pump also)

I’m lost. What can I check now? Isn’t much left expect injectors.

 

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I was honestly debating this tonight as it has 2 new batteries but they only had two in stock so it is one battery short. I didn’t figure this would cause an issue as the motor sounds like it’s turning over enough.

 

the yellow check engine light is coming on while cranking

 

Had a mechanic come out with ET and there weren’t any codes and he said he didn’t notice anything out of the norm but that he wasn’t just real familiar with the acert engine. What are some key things that I can have him check with the ET that would prevent it from cranking?

I've replaced the cam shaft sensor and the crank sensor with no luck.

 

It is seeing both of those and I also replaced both sensors since he checked with ET, I didn’t know if someone may know of some other parameters the computer looks at in order to start.