Mystery problem

[Papafrag2299]

So I have a 1990 f250 4x4 7.3 idi with a presumed 195,000 on the clock. My problem is there is alot of light grey and white smoke with a cheech of black when you punch it. It white smokes at idle and when you press the throttle. It also has a miss. I have new return lines and fuel filter. My brother when he drove it had put jet fuel in it. I drained all of it out and put diesel in. It is unusually hard to cold start, and after it sits for about an hour after you run it, it takes awhile. While it is running the is a huffing noise from the exhaust, like a exhaust valve is stuck open. Any help would be appreciated.

 

[IDIoit]

do you have coolant loss?

 

[retiredinhomer]

do you have coolant loss?

OUCH somebody always asks the tough questions and does it have a coolant smell?

 

[IDIoit]

OUCH somebody always asks the tough questions and does it have a coolant smell?

the gray smoke has me leaning this way, it sucks to diagnose a significant issue, but has to be said....

 

[Chief]

How’s your oil consumption?

 

[IDIBRONCO]

The noise in the exhaust is usually bad exhaust valve guides. 7.3s are kind of known for this. The guide wears and then the valve doesn't seat completely. The "hard to cold start" issue sounds like your fuel is draining back. You may have an air intrusion issue. If you're sucking air in while the engine's running, that could explain the smoke. If you have bad valve guides and keep driving the truck like it is, you could end up with something like this picture.

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[dgr]

It is unusually hard to cold start, and after it sits for about an hour after you run it, it takes awhile

Jet fuel doesn't have any lubricant. Good stuff when it's free. Add some outboard oil to it.
If I read that right, once your truck is started and has sat for awhile but is still hot, it is hard to start. Try pouring a bottle of room temp water on rear part of the IP. If that fixes it, you need a rebuilt pump.

Hard start cold and white smoke could be glow plugs or air intrusion. Test light from battery positive to each glow plug will test the plugs. Substitute a piece of clear tubing for the return line to the filter head to check for air intrusion.