92 F-250 smokes when let off throttle

[Red Sled]

92 F-250 7.3 idi nonturbo.........The truck smokes and by smoke i mean really really smokes when you let off the throttle but the kicker is that it only does this if there is a 1/4 of a tank of fuel or less, oh and the smoke is blue, so i think that means air in the fuel. The truck has dual tanks and it does it on both the front and the rear tank. If there is more than a 1/4 tank it won't smoke at all. It just started doing this about 5 full tanks ago so i think that ruled out bad fuel. I have used additives to the fuel to make sure everything is clean and lubricated and it still does this. All of the fuel lines are new within the last 2 years, new injector pump 8 months ago. Is this a lift pump issue? Any help would be greatly appriciated.

[cdnsarguy]

I would consider there is an air intrusion somewhere......... normally at 1/4 tank the fuel pickups can/will break off and suck air since the fuel is not getting pulled in due to sloshing around......... visit my photo link there should be pics there. You would need to pull the senders or drop tank(s) or lift bed off to inspect rear tank.