My 2003 tahoe spins over but won't start ?

Look under there and see, but I think they (the hub locks) are engaged by vacuum motors.

Disconect the fuel fed line into the fuel lug that runs the fuel injectors,check for pressure ther,also try to listen for the fuel pump kick in when the ignition is on possition.

Are you saying the engine cranks but won't start, or the engine won't crank ?
If the engine does not crank, you would check for voltage at the starter, the neutral safety switch, and the key switch as well as the ground connections.

It wouldn't hurt to check fuel pressure with a fuel pressure gauge. you should see somewhere around 48 - 55 psi. the test port is on the fuel rail about in the middle of the rail and on the drivers side.

If the fuel fuel pressure is low it wouldn't hurt to make sure there is power to the fuel pump before condemning it. Power is supplied to the pump by the larger of the two grey wires.

The fuel pump is located in the fuel tank and the fuel tank will need to be dropped from the vehicle in order to service the fuel pump.

If you decide to replace the fuel pump get an a/c delco or a delphi pump. These are the best two option for your vehicle. Do not get an airtex brand. They are not reliable pumps although they are cheap.

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Many possible causes....Too little info to make an intelligent suggestion. Try charging the problem vehicle's battery with jumper cables for 2 minutes with the supply vehicle running at fast idle (or about 1500-2000 RPM, if it is tachometer equipped) before you try to crank the problem vehicle on a cold morning. If it starts right up, you likely have a weak battery that needs replacing.

Did you put stablizer in the gas before storing it? Does the fuel pump run for 2 seconds when the ign is turned ? Have you checked the air cleaner for debris? Do you have spark? You must have air/fuel/spark to start.

could be starter relay or starter check batt terminals & grounds.

My suspicion is a starter going bad. Sometimes when starters get old and worn they will start good when the engine is cold but not when the engine is warmed up. Did you perhaps notice that lately is seemed to drag when you tried starting, especially warm or it seemed to crank a little slower? I'd replace the starter. Hope this helps.

Now you have a good battery & a starter that turns over the motor

Have you cycled the key on & off with a fuel pressure gauge on the
fuel rail?

Do you have a fuel filter that isn't over 3 or 4 years old?

Have you checked for spark while cranking ? Use an old plug on the wires,
if you have ignition wires,don't ground the wire without resistance

If you removed the ducting & MAF Sensor it won't start

Tell us what you checked & exactly how that was done.

That "thing" is part of the compressor clutch. When it’s spinning the clutch is engaged, when it stops the compressor is off. If it’s constantly cycling, you probably don’t have enough freon in the system. But remember, however the gas escaped before, it will escape again, unless you fix the leak.