[Airjer_]

I think what you are describing is a crank no start. It will crank all day long but will not start. Just to clear that up.

Fuel pressure is the key. These injectors are a poppet style meaning they rely on a specific minimum amount of fuel pressure in order to operate correctly. This should be at least 60 psi. 1 psi can be the difference between starting and not starting. Not starting pressures are usually 57 and less PSI. Typically they will start with more that 58psi.

The symptom you described is a classic symptom of low fuel pressure. The reason is starts and continues to run with a shot of starting fluid is once the engine starts the poppets are under a vacuum and require less fuel pressure to "pop" open.