Quite a strange problem this. My Fourtrak had problems starting lots of smoke when it eventually fires), needed to crank it a bit and put the glow plugs on a few times, so I replaced the glow plugs and tested the rest of the system worked ok. Still had the same problem, tested everything again, seemed ok. I then looked at the fuel side, I'd replaced the hoses from the tank to the engine (feed & return), changed filter (which had plenty of rubbish in it). Still the same problem, checked for leaks in the system, there's no signs anywhere and I've done the brown paper trick to double check. After reading in the Difflock mag about possible starting problems, bleedback may be the cause, I hooked up some clear tubing from the fuel supply and return, started the engine ( a couple of times to get fuel through both pipes. Started up and watched the fuel return, air bubbles in the tube, clearing within 20 seconds, theres not a lot of bubbles. I stopped the engine and watched the return, and found that the fuel was being sucked back into the return pump, pulling air through. I'm guessing this is my problem, it's strange as starting is only a problem when the traks been stood (ie in a morning and coming back from work), smoke clears pretty quick and I have no other running problems, starts from warm with no problems, no change in mpg (around 31 combined), has anyone got any ideas of what I can do next to try and eliminate this problem.