88 F250 will not start
 

You could try this.
Remove one of the spark plugs after trying to start it.
If it is wet at least you know it's getting fuel.
Also, check the intake system for being clogged possibly by an invader that has decided to make a home there. I have seen some mouse nests that absolutely allowed no air to pass.
Do you know if there is spark available after the backfire incident?
Also if possible try to confirm that the rotor is pointing to the # 1 cylinder when the pulley is on the TDC timing mark. Before that with the cap removed make sure the rotor is turning . Let us know what you found.

Thank you! I will take a look this weekend and will post the out come.

Sorry, it took awhile to get back to you. I also made a typo it's a 1989.
I worked my but off this weekend trying to get it started. It was 106 here yesterday and of course no shade where it is parked. I look like a lobster today.
The last thing I did was replace the fuel filter and it started. I was like could not have been just a fuel filter. It ran for about 10 seconds (real ruff but ran) then cut off and would not start back. The exhaust smells like old gas. Going to drain gas tank if I can figure and easy way to do it. (No drain plug that I can see, Can't run siphon hose in tank.)

Any suggestions will be greatly welcomed.