when im driving down the road my truck started defueling and if you try to give it more gas it throws out white smoke..it does it when im taking off and when im goin down the interstate.. what could it be

 

white smoke on a 12V

Perhaps your timing has slipped... its my guess..

Tx

 

Are you still using the original overflow valve? It should be worn out by now. If it relieves too much fuel pressure due to a weak spring you will not have enough fuel pressure in the IP. Low pressure could result in fuel starvation at the injectors and white smoke.

 

check your pre screen and change fuel filter,and the air cleaner.