alright guys i need some help with a diagnosis the truck is a 2002 4500gmc with 76000 miles
its not mine so im not as knowledgable on the history as i would llike but it recently developed a problem of excessive white smoke at start up this lasts until the engine comes up to temp this will last several minutes any suggestions as where to look what to test who to shoot?

 

well white smoke is raw unburnt fuel so either an injector sticking and letting too much fuel in or it could be an injector pump issue. other than those two the only other thing it could be is bad piston rings i believe

 

i would say a bad injector ^ what he said

 

how can you find which one is there a diagnostic tool to buy that can systematicly short injectors to find the weak link?

 

i just had my injectors replaced for white smoke at idle when warm, try to smell the smoke , if it smells sweet it could be coolant (head gasket?) or if it smells campfire ish it is most likely fuel. Most likely injectors, Is there fuel in the oil? check the oil level and see it it is growing above the full line.