270 CDI failing to robustly start after injector seal replacement

[Andy The Bubble]

Hello All.
I would appreciate some help.
I few weeks ago - I replaced injector number 5 copper seal because it was blowing gases and partial combustion tar. Before this - the vehicle started every time, even it is was a longer crank than originally known.
To remove the injector, I used a special toolset - all went well, however I was mindful that I was removing many small pieces of the injector solenoid mechanism.
Once the injector job was complete, the engine started eventually and ran smoother than ever. However, it would not re-start when the engine had been previously started, not just a warm coolant.
Therefore I am adamant that it is not building up enough fuel pressure to start sufficiently because it is pulling in air at some point.
So only when it is left alone (overnight - on charge, - will it start)
I have replaced o-rings on pipes, re-built the injector head, changed the crank sensor, but I have this issue.
Unfortunately my generic tool has not pulled any DTC's
Is it possible the injector is partially damaged, closed during cranking, causing a low pressure as it is spilling into the return line?
Whilst the engine was running, there were bubbles in the lines, but the cleared away.....

 

[DieselPete]

I think if the injector was stuck closed it would still start but run badly if stuck open you would suffer with low rail pressure, air in fuel lines may be the problem and also check wiring plug on top of injector as if ones comes loose the engine will not start. You may have to get star plugged in and do a real time diag on it rail pressure and injector values just to rule them out, are the pipes tight to the injector and rail? Check everything again just incase. Good luck

 

[Andy The Bubble]

Thanks for your help.
I believe it may be stuck open, explaining the low pressure.
I will check all the connections, etc,
I am considering buying a single good injector and doing a swap...

 

[carat 3.6]

A leak off test will confirm if the injector is leaking internally, in my opinion once those injectors have had the insides disturbed they are considered suspect.