Long read ahead but important things are bold.
I have a huge problem with my W124 Diesel and was wondering if yall have any ideas. The car is a '87 300TD with a leaking injector pump. The leak can be seen where the pressure valve holders thread into the injector pump. I decided to fix this in an attempt to fix my terrible idle and get the car running better.
To fix the leak, I R&R the copper washers under each pressure valve holder and the rubber o-rings too. In addition, I replaced the main fuel filter and the pre-filter. Naturally, I introduced a bunch of air into the system.
From what I've read, air must be bled from the system by cranking the engine for 20 seconds at a time (allow sufficient time between cranks to charge the battery and let the starter cool).
I've diagnosed the problem up to the injector pump. I've got fuel going into the injector pump (visual check at each joint, i.e. make a mess) but nothing comes out!! 
The weird part is, if I crack the pressure valve holders, it shoots fuel out like a fountain. However, if hand tighten the holders just a little bit - no fuel! I'm talking about two fingers tight - no fuel!
I've done a few other tricks to coax the air out:
- Filled both filters with fuel.
- Blocked up the return line. There is no fuel returning to the tank.
- Bypassed fuel thermostat. It was leaking.
- Checked for leaks. No leaks but where is the fuel going!?
Any ideas, y'all? This is very frustrating
