Diesel not getting to injectors

I drove for about seven kilometers with the water separator warning light on, and emptied it when I got to where I was going. When I started the car again, it had very little power and the revs varied between 200 rpm's and 1500 rpm's with my foot to the floor. After several times turning the car off and on again it eventually cranked but would not start at all.

I replaced the water separator and the fuel filter. I checked the fuel filter for damage or gunk or any kind of excessive build-up; there was none. I bled the injector pump by loosening the fuel shut off solenoid and operating the primer pump. After several pumps the pump got harder, I pumped several hundred milliliters of diesel out from around the loosened solenoid.

I tightened the solenoid valve again, then cracked one of the nuts connecting an injector rail to the injector. I cranked the engine over and even sprayed a good squeeze of ether in to the air intake before I did so. The engine gave a rough grumble for a second with the ether but promptly died and refused to start.

I have pulled off several hoses to see how far the diesel makes it when I pump the primer. I can get diesel coming in to the intake of the injector pump, I can also get diesel coming out of the return line to the tank, and I can also get it coming out around the solenoid valve when it is loosened. But no matter what I do I cannot get diesel to come out of the injector rails.

Also the first thing I did out of everything was drain about a liter of diesel out of the bottom of the tank to make sure there was not a build up of water. I have since put 15 liters of fresh diesel in there, bringing it up to around 2/3 of a tank.

So my question is broadly, why wont it start? And more specifically, why can I not get diesel to the injectors?

Thank you very much in advance, any help or advice is massively appreciated.

Lyndon