Recently I've noticed in about 40 degree weather that my truck takes about 3 sec of cranking and just dumps white smoke like a son of a gun. But that's after I run the glow plugs one or twice if it's colder. To me it seems like the glow plugs are staying on 15 seconds and my owners manual says in 40 degree weather it should only be on for 5-7 seconds. I recently had to do the 50 cent mod and tested the glow plugs they were all in reasonable resistance levels so could it be my glow plug relay? The shop I use to work at did numerous 7.3's for this issue but that was a complete fail. Could mine just be on its way out?

 

How many miles are on the truck? I'd say after 11 years the relay is probably on it's way out. I would also look into replacing the GP's with motorcraft only!