I picked up a euro model 83 300D over the weekend. It had been sitting for a while and would crank but wouldn’t start. I started off by bleeding the fuel system And I was able to get it to almost turn over however the diesel in it was pretty old plus an injector return line appeared to be leaking. I drained the tank and filled it with new diesel. I also changed the fuel filters, the leaking injector return line, and the rubber fuel hoses around the fuel filters. Ever since I did all that, I haven’t been able to bleed the fuel system fully. I can hand prime it and and get diesel to come out of the return lines on the secondary fuel filter housing, but nothing will come out of the injector hardlines, even when I crank the engine over for a while. I replaced the hand primer pump today and that didn’t fix anything. I also inspected the fuel lines and fuel filters for any cracks that could be sucking in air and didn’t see anything. I’m honestly not sure where else to look.