Possible Bleeding Issue

Hi All, I have been working on a friends ZD30 DDTi Patrol
last time they drove it it just gave a great shudder and died.
After consulting with a few so call mechanics,
They were told it was either their fuel pump or a dirty filter.
After a couple had tried to get it running, with no luck.
They then bought it to me.
I am by no means a mechanic but I do own 2 TD42 Patrols.
So decided to have a go. I decided the issue was air in the fuel.
Bled the system from the primer pump to the injectors and away she went.
Run for about 5 minutes and was reving and idleing no problem at all.
Then it shuddered and shut down. ggrrrr
After checking again found air in the system.
To cut a long story short an Army mate told me to check for blocked breathers on the tanks.
Opened the tank and got a hiss of air from vaccum in the tank.
Used the compressor to clear blocked breathers and bled the engine again.
This time no problems she running like a dream.
The problem being Blocked tank breathers cause a vaccum in the tank.
The injector pump cant suck in the diesel so it sucks in air from the weakest point in the fuel line.
Resulting in an injector pump and injectors full of air.
So before you start pulling out your hair, Clear your tank breather lines.
Hope this will help someone
Cheers all