X15 fuel pressure to fire?

[LibertyDiesel]

Whats the bare min fuel rail pressure to fire?
and how much pressure is rail supposed to hold, say overnight?

Im having a crank no start, X15, low fuel rail pressure.
cranking im getting 1450psi. commanded is 5600psi.
After done cranking, rail pressure drops to 150psi.

will fire with ether and then stay running on its own.

we changed the relief valve on the rail. and installed new high pressure fuel pump.

last fuel pump would only crank to 900psi, thats why we changed it.

so now were back to square one.

lift pump seems to be delivering, sounds good, blows out out the brass filter checker fitting like a hose.

I think i might finally buy the fuel line caps, but until those come in, what else?
major return leak im thinking?