Low compression is a possibility.
It is a 99.5 250 with 368k on it.Slow cranking is a very real problem, and the likely culprit if you're not smoking. I never get more than three years without one of the batteries failing, and I always replace them as a set. You haven't listed year, model, mileage. I'm surprised that you have had to change the starter more than once.
Which relay im having simular problem. New batteries glow plugs glow plug relay valve cover gasket and still no start unless plugged in and sits for more then a day.Correct me if im wrong, but if its smoking, doesnt that mean that your spinning the motor fast enough to get the HPOP to fire the injectors? I bet its your relay. I had to replace mine not 3 weeks ago..... It wouldnt even start in the middle of the day when it was 85F out. That was a week after I changed out my Injector o-rings on RT's suggestion. Now that I changed the relay, it starts first try, even in 35F temps at 330am.
You should start a new thread with your issue. The last post on this thread was Sept. 26th 2012 so, I doubt you will get a response. Sorry, I don't have an answer for your question but, if you start a new thread you will likely get some responses. Good luck!Which relay im having simular problem. New batteries glow plugs glow plug relay valve cover gasket and still no start unless plugged in and sits for more then a day.