2002 Denali, wants to start but dies. Fuel pump is good, get spark. Help me please

What is missing from the firing;
Air, Fuel, Compression and spark.

02 sensor is not you main problem.
Have you got good spark and fuel pressure when it acts up or quits?
Is it dead now or just acting up?

Pull the throtle body and replace the base gasket to start with.
Clear codes and see what comes back.

Check fuel pressure when it quits.
Post back fuel pressure readings.

Get some good repair info on the code for fuel pump relay and fuel pump and fuel pressure.
Let us know how it goes.

Crank or cam sensor sounds like, if you can get a code scanner that would help narrow down what's up if the ECM is good

Ignition module needs to be checked, Faulty PCM. possible, Vacum , leak and or Mass air flow meter.

Ignition control module? Bad grounds? Fuel pump relay? Bad compression? Timing chain or belt? Better start troubleshooting and stop throwing parts at it. This could get expensive in a hurry.

Does the starter crank the engine over? If so, check for spark on a spark plug wire when cranking. If you have a strong blue spark, ignition is probably good. Check fuel pressure. Do you hear the fuel pump turn on for 2 seconds when turning key to on?

Does the dash lights get dim when it dies out ?

If it is flooding,fuel is not the problem.Sorry you did a pump already.You need to check spark and air,I would start with spark.Check your plugs for spark.If they all spark normal,that also means the ignition coil is good.That leaves air.Check the filter and intake hose for leaks,holes,etc.I would guess spark,but you never know what you'll find.If you are not 100% sure how to check spark,sounds like you probably do though,just comment on this post and I get an auto email linked to here and tell you the best method.Good luck! Greg

1. use scanner to find out if there's trouble code.

2.. it's not clear if the starter (motor) turns as you try to start the engine, if not, check starter motor including intermittent (maybe) problem with the ignition switch.

3.if starter motor turns everytime you try to start: check the electrical ignition system: coils & spark plugs

Try swapping out the fuel pump relay, if thats good try testing your ignition system components. Start with the module and coil pack. If they are ok check the crank position or cam position sensor (which ever applies).