Bleeding Diesel System

[a2t]

Im trying to purge my 87 300D turbo after frybrid veg oil kit install. I installed the frybrid kit, which requires some changes to the diesel routing as follows :

Diesel in goes straight to in side of main diesel filter (instead of to pre-filter, then lift pump, then intake side of main filter).

From there, it comes out and into a solenoid valve. From that valve it goes into the OEM fuel heater, then lift pump, then IP.

So I unhooked line from heater to lift pump and hooked in a mitivac vacuum pump. Im getting tons of air bubbles – should this ever seal up or will I always get air under normal circumstances? Is there a better way to bleed out fuel system then what Im doing? Can I bleed past either the lift pump or IP, or will that not be possible? I know I have to remove the banjo bolt on the return side of main filter and plug the hole, but I haven’t done that yet. I wonder if that is causing all the air bubbles?

Is it necessary to bleed the return lines back to tank? Or will that just work itself out once engine runs?

Thanks in advance.