desel to gas back to desel will it pass emmission test?

Where do you live that there testing diesel emissions?

--Added-- I ask where you live because in California, diesel is exempt form emission test. So if you went back to diesel you would just need to see a state smog referee to verify this but that’s in California. I wouldn't pay too much attention to some of the idiot comments below. They have obviously never picked up a wrench before or heard of a diesel or gas conversion. If for some reason you live in State that check diesel emissions as long as everything is put back to original and is running fine you shouldn’t have any problems.

Charlie F a diesel engine uses diesel fuel & a gas engine uses gasoline . You should not mix them there would be many expensive problems .. The veichel should be marked clearly as to what fuel it uses . Check around the fill area . If not check the owners manul or check with your local dealer or garage .. Off hand I can't think of any states that check emmisions for diesel .. More than not emmission failure is due to a tuneup . Goo Luck

WHAT???? Either an engine runs on diesel fuel, or it runs on gasoline. Not both. Not gonna happen.

For an emissions test, maybe you can put in some 104-octane booster from your local auto parts store; run that bottle in the tank before the test. Make sure to have a recent oil change and air filter change soon before the test. ALso, if you're really worried about the test, maybe an O2 sensor and PVC valve change.

You'll need to check with your state about your emissions requirements on diesel or gas. even though the truck was a diesel you will have to do emissions for what ever engine is in the truck now. You can have an emissions test done on the truck before you buy it to see if it will pass.