I have a 1999 gmc Yukon it is getting fuel and spark i even sprayed starter fluid in the intake but it still wont start it turns over good but wont start

Try some engine starter fluid. Spray in the intake and see if the engine will at least try to start. If so, you have a fuel problem. If its fuel injected, something could be keeping the injectors from opening.

no. timing belt must work in order to operate spark..

If you have to spray fluid into it then it sounds like the fuel presseure is not there, get a fuel pressure gauge and see what the pressure reading is, then leave it hooked up for what ever time it takes to not start, before you try to start it check the pressure, if it has dropped then your fuel injector/s or fuel regulator is leaking, crank the engine after taking the reading, the fuel pressure should come back, 60-66 PSI, Vent the fuel tank vapors by loosening the fuel cap.Position the ignition switch and the A/C system in the off position. Install a fuel pressure gauge to the vehicles fuel pressure valve. and with the keyon, engine off verify the PSI reading on the gauge.
Anything less than 60 psi and your fuel pump is weak

Determine if it's more of a spark problem or more of a fuel problem.

If it turns over vigorously, then the battery and starter is good.

If it won't start even though it is turning over, then I would spray some starting fluid into the intake and see if it starts momentarily or for a few seconds.

If it does start, then you know you have spark, but no fuel delivery. In which case it could be a bad fuel pump or fuel injectors aren't firing.

If it doesn't start even with the starting fluid, then you may not have spark.

Good luck on this diagnosis.

one answer is lack of compression in the cylinders,normally associated with high miles.
could also be valve seats/spark plug gap/dirty air filter,there are a few more but start with the cheapest to diagnose and work up.....

Check your fuel filter, fuel regulator, and fuel pump. It sounds like you are starving the engine of fuel.

yes you should be able to hear the fuel pump run for about 5 seconds once the key is turned to the on pos. check to make sure you have spark. if you do try having someone spray air intake or carb cleaner into intake manifold while you crank. If the truck starts right up for a second (or stays running as you keep spraying) Id say you have a bad fuel pump and id change the sending unit also. (First check the fuel pump fuse and fuel pump relay) GMC and Chevy are nororiously known for having bad fuel pump/sending unit problems. I have prob changed over 60 myself.

A 1999 GMC Yukon has a fuel-injected engine. They are known for the fuel injector lines inside the intake plenum to break and flood the engine. If you are pouring starter fluid and gas in the intake you are only making it worse. replace the injector assembly with the "new improved" injector assembly and replace the plugs, then it will probably start.

This subject is covered by GM Technical Service Bulletin No.: 00-06-04-003B

See GM Parts List below. This replacement Injector assembly is now also available in the aftermarket.

Sounds like a fuel pump. You can have your SUV hooked up to a fuel system pressure gauge and see if you are getting 36psi or higher. Anything under that and you have a bad pump.

Sounds like a security problem that is preventing starting. It will run for a few seconds and then die.