I have an 82 300sd that I converted to run on waste vegetable oil. I am in hawaii so it is a single tank system. I have removed the stock filter and added two stanadyne fm 100 filters, a 30 mic and a 5 mic. The fuel lines have been replaced with biodiesel compatable, and they go through a flat plate heat exchanger and electric boost pump before going into the injector pump. There are no (more) leaks.

The problem is the car will somehow get a bunch of air in the fuel system. I will bleed it and bleed it for a really long time and it will finally start running again. It will run for about a week or so then just die out again. It's really frusterating because it makes me think I fixed it and then it happens again. I have checked all my connections and made sure they are tight, non are leaking.
If I take off the fuel line that goes to the tank and put it in a jar of biodiesel or veggie oil it will bleed very quickly and start and run fine. I have replaced the primer pump and injector return lines reccently. The car will have the same problem regardless of the fuel. I don't know what to try next? Can anyone help? ALoha