The trouble your having is why I put a cheap electric fuel pump near the tank--not only do I leave it on while driving(seems to run better )but if I run out of fuel I can open the bleeder on the big filter on the firewall and let the electric pump fill the filter and lines,it also seems to reduce the amount of cranking time needed to bleed the system.Once you are getting fuel to the injectors it should start right up(the glowplugs might need to be activated even if its warm out)--if it wont fire up you could try the wd-40 as suggested,but DO NOT activate the glowplugs if using any type of wd-40 or other starting fluid--in fact,I would save the ether for your lawnmower--it kills 6.2's.
If you cant see fuel at the injectors after much cranking its time to start looking for an air leak in the fuel line from tank to pump,my K20 had several,the steel lines had just enough rusty pinholes to let air in,but not drip diesel out,cracked rubber hoses too--I had to get the truck running when I first got it by putting the lift pump fuel line and the return line in a bleach bottle full of fuel--it finally started and ran,then I found the air leaks.Have you changed the fuel filters?(you may have 2,one big one on the firewall,some have a secondary filter hidden by the air cleaner near the back of the motor,in front of the vacuum pump.Dont do what I did and forget to fill them with clean fuel first--I had one hell of a time on a customers truck,cranked it so long it fried the starter, /forums/images/graemlins/blush.gif /forums/images/graemlins/frown.gifand we cracked lines,pulled the pink wire,nothing worked until we got the new starter in,I think the increase in cranking speed is what finally got it to bleed and fire up.Fully charged batteries are a must in this situation--cranking it slowly with weak batteries wont work,and will fry the starter due to the lower voltage.Ask me how I know this! /forums/images/graemlins/angryfire.gifAlso check and make sure you are getting power to the fuel shutoff soleniod on the injector pump when the key is on you should hear it click if you pull the wire off and on.Good luck and I hope you get it started--diesels can be a pain when they run out of fuel. /forums/images/graemlins/crazy.gif