If you have a 2n gen fuel filter head and are constantly bleeding air out of it then you need to address the source of the air. The CRD uses the same fuel lines as the gasser but and it's a big but the gasser has a fuel pump in the tank that keeps the fuel line pressurized while the CRD has a puller pump on the front of the engine that sucks fuel from the tank. Nothing wrong with a puller pump as they have been around forever. However, the quick disconnect fittings that keep fuel under pressure from leaking out don't always do a good job of keep air from being pulled in given the use of a puller pump.
If you have a bad air leak at those fittings I'm not sure an inline fuel pump will help. Alternatives included:
1. BlackLibertyCRD's automatic bleeder - involves messing with the somewhat fragile plastic fuel return block
2. in tank pump - $s and requires dropping the fuel tank.
3. replacing the quick disconnects with marine diesel rated fuel line - not much $s but does require dropping tank.
I'd recommend the latter. See
http://www.auerbach.ca/kj/lift_pump/ for instructions on installing an in tank pump that include how to drop the fuel tank. Just a note only the quick disconnects on the fuel supply line need to be replaced; those on the return line can be left alone.
PS some have installed a lift pump in the engine bay on a bracket by the battery. I would not recommend putting one inside the cabin for obvious reasons.