blue white smoke at start up when cold.

[Govt issue]

1995 6.5 td non egr. blue white smoke at start up.
new engine jasper 15000 rebuilt injectors and pump at time of engine. Just started haveing this problem. engin will miss untile smoke stops,about two min.

[ucdavis]

The miss coupled w/white smoke (unburned fuel in exhaust) may indicate failing glow plugs or glow plug controller. If you have the old AC9's (or even AC11's that are old enough) they do wear out (the 9's may also break in the pre-combustion chamber). Kennedy sells an improved plug for $80/set of 8 that give faster glow, don't expand/break, last forever and fix breakfast for you (at least the first 2 are supposedly true; haven't experienced the latter ones yet).
Controller should click luodly when turning key to run (not start); voltage across the two controller studs should be battery voltage w/key off and from right stud to ground should be ~10.5V w/key on, engine off when controller clicks (sending voltage to high-ohm glow plugs).
There are other causes as well- air leak in fuel injection system, etc. The timing thing could be the culprit, but I'd expect you to have poor running to some extent after warming up. See Members Area, scroll down to Reference, and click on Diagnostics; see the chapter on White Smoke. The rest of the Diagnostics makes fun reading too.
Good hunting.

[charliepeterson]

Another simple test is to unplug the coolant temperature switch (beside thermostat housing) and try to start the truck. With this unpluged the computer defalts to -40* and increases the glow plug duration. If this sensor is acting up the glow plug system won't work as advertised.

I second the good advise from ucdavis.