my truck has been smoking upon start up but clears up and runs o.k....any ideas?

 

White smoke on start up is unburned fuel.
Probably a glow plug or two are bad or weak? Still cold where you are located?

 

checked the glow plugs with a test light by removing the wires to each plug and connecting one side to battery ground and the other to the glow plug and everyone checked out o.k.....anymore ideas........the weather here is not cold at all(Hawaii)

 

A little white smoke at start up is normal, especially for older engines.
It may have a slight misfire and smooth out as the smoke dissipates.
An ohm meter will tell you the health of the GP.....should have less 5 ohms resistance...

 

mine does the same thing, but it also has a kinda long crank time. It is definatly unburnt fuel, I am thinking it is an injector bleeding down overnight or perhaps the check vave in my return line at the pump not working properly.

 

my truck has only 62000 miles ....I just changed the GP controller cause I noticed some melting stuff from under the controller...don't think it had anything to do with the problem since it was still starting up but it just did not look right,looked like it might have overheated...anymore good idea's..the truck starts up quite mormal but at times (not always) it will start and run rough until the white smoke clears up.....?