2005 ford f250 FX4 6.0L diesel. Hard to start all the time. takes about 5 seconds to start.seems like starts quicker if I turn the key to the on position and live it for a few seconds more after glow plugs light goes out.

When light goes out glow plugs still heating so count 15 seconds after ligh goes out the crank on key

Sounds like you may have a high pressure oil leak, if you check the oil resevoir level before you start the truck you may find it low or empty. Its located at the front of the engine in front of the fuel filter housing, there should be a threaded plug you can remove to look in, if its empty or looks low, fill it up with the proper oil and put the plug back and try it then, if its ok now, you likely have an oil leak, typically failed o-rings on one or more injectors. You can buy injector o-ring kits but its a fairly involved job, I am a Ford Diesel tech and it usually takes me about 3 hours to replace all the o-rings on all 8 injectors, first time for someone who's never done it will probly be closer to 5 or 6 hours.

sounds like a bad glow plug module

file pump

If you are talking about the new ford ford 6.4 diesel or cummins or duramax, it will take a little longer. They are common rail and pressurize the diesel directly with a pump, the 6.0 uses high pressure oil to pressurize the diesel in the injector. Because of the extra step it can take longer to start the engine.

the pump is part of the filter/separator not in the tank no fuel will come out if filter is removed make sure there is fuel in the upper filter if there is the pump is ok it might be an oil pressure concern

Do mean you have hard time communicating with a scanner at the OBDII connector, if so make sure you power at pin16 at diagnostic connector, also we have seen issue with glowplugs not working properly causing hard start when cold and starts fine after warm-up
You can check for glowplugs operation at initial key-of before cranking by checking for voltage at each glowplug connector with a multimeter.

It is possible that some of the glow plugs might not be working. This will cause a hard start and smoking condition especially in cold weather.

I have a 2005 Ford F250 4x4 supercrew, When I first start the engine the truck has no power and will not run good until it warms up which takes about 5 mins. How do i fix this

check your fuel pump you might have a weak pump or you might also have a glow plug or plugs out.