Out of gas... I'm baffled

[marcschatz]

I have an 84 300TD and I have some issues with the fuel delivery system. I have replaced both fuel filters, injector bypass lines (they were leaking a lot) and the fuel lines in the engine bay and directly in front of the tank. I recently discovered the small (reserve?) tank behind the spare but have not replaced the lines to it. My car didnt have a fuel strainer in the tank. After issues with the primer pump on my fuel pump leaking a lot (now need new engine mount) I replaced that with an updated model. However, my car STILL runs out of fuel! It will be fine and I can drive for 10 miles or so at various speeds and then the thing just runs out of gas (diesel I know)! I have to get out and pump the primer pump for a while, usually til I can feel there is fuel in the lines again, and then I can 'usually' start the car right back up and go again for another 10 or so miles. When it does start back up, its just barely running and I have to pump the pedal a bit until it gets up to speed and then I can go. Im baffled. IP? fuel pump? Posted this problem on the other list with no help. Anyone ever hear of anything like this? I did buy a fuel pump vavle replacement kit, but havent had the guts to try installing it yet.
Help!