Hello, I've been following your post and want to put in my 2 cents. I believe your system is based on the GM OBD 1 system. The fact that you can make this engine run if you feed it gas leads me to believe your ignition side is fine as are the sensors that relate to spark. I believe those are the Crank and CAM position sensors and Your distributor must be in place properly. When you first start up, these systems run in open loop which leaves out a bulk of the sensors that deal with fuel mixture like MAP and so on. You mentioned that your fuel pressure was down around 30psi. That seems low for fuel injection. Thought these need a minimum of 45 psi and closer to 60 to have the right amount of fuel volume introduced during the specified injector firing pulse width. Have you looked further into either your fuel pump or pressure regulator? If these are fine, and you go back to ignition, I would look at your helm safety switch and ignition switch as you mentioned your alarms aren't consistent. Does it try to start when cranking but die when you release the key? In summary, the fact that it runs when you feed it gas takes me to a weak fuel pump or something in the pump interlock circuit that takes away power from the pump. May your luck change and the wind be at your back.
