i have a 98 grand prix 3.8 and ac went out so i start driveing my ford sat for about 2 years put new gas and it will not turn over back fired on me a couple of times

It ran fine when you parked it? If you didn't put fuel stabilizer in it when you parked it then you probably have a gas tank full of paint thinner. http:/ /www.priproducts.com/FAQ.cfm there may be a space that gets added to that link so delete it. Does the gas smell like gas?

You can remove the fuel pump relay and spray some Carb cleaner or starting fluid into the intake and see if that starts it.

Yes sir i tryed to spray crab cleaner in there replace spark plugs and wires yes it ran fine just ac went out on it could not afford to get that fixed so i just drove my work car around decided to take it for a spin when that happend took off plug one to see if it was getting spark and it was now im kinda dumb founded

Yes it does and replace the fuel filter too

I agree with john ur gas is no good try what john said but also buy a bottle of fuel stabalizer and put that in too just remember to use the recomended ammount or ur in for more problems. It will still take a few trys of crankig it over but thats normal

Smell the gas that is in the tank if it smells degraded you should get all the gas out of the tank and put new in. If it still smells normal you should be fine just adding gas to it. I wouldn't use any additive right away because you might dislodge to much varnish and sludge in the fuel system. Save that for later once you have it running some what smoothly. As far as backfiring, that could one or more of several issues; sticking valves, plug wires, plugs, injectors or even a sensor issue. If you can get it started with starting fluid try to keep it running by giving short little bursts of fluid.Once the engine warms up many of the potential issues you have will subside.