My engine will not start up and run

This sounds like the crankshaft angle sensor or the fuel pump has gone out, when you turn the key to the on position without cranking the engine over can you hear the fuel pump run in the tank for 5 seconds? These guides should help us fix it.

https://youtu.be/dCjmRL3p4Cs

and

https://www.2carpros.com/articles/car-cranks-but-wont-start

Also, lets run the codes to see what come up.

https://www.2carpros.com/articles/checking-a-service-engine-soon-or-check-engine-light-on-or-flashing

Please run down these guides and report back.

You may need to bleed the fuel system.
Open the air bleed valve on the fuel manager/filter.
Connect a hose to the air bleed valve and place the other of the hose in a suitable container.
The diesel/water mixture is flammable and may be hot. To avoid personal injury or property damage, do not allow the diesel/water mixture to come in contact with skin, open flame or a hot engine. Do not overfill the container holding the fuel mixture as heat from a warm engine or any another heat source may cause the fuel to expand and leak from the container that may lead to a fire.
Remove the F/SOL fuse from the fuse panel.
Crank the engine in short intervals of 10-to-15 seconds until clear fuel is observed at the air bleed hose (wait for 1 minute between cranking intervals)
Remove the hose and close the air bleed valve.
Install the F/SOL fuse and start the vehicle. Allow the vehicle to run at idle for 5 minutes.
Check for fuel leaks, and clear any Diagnostic Trouble Code's (DTCs)

Good morning,

Can you hear the fuel pump run when you turn on the key?

Did you check for spark? When you crank the engine, does the tachometer move up a little?

https://www.2carpros.com/articles/how-to-test-an-ignition-system

Does the check engine light on with the key on?

Trying to see if the engine systems are working.

https://www.2carpros.com/articles/car-cranks-but-wont-start

Roy

We need to check a couple things first. You said the vehicle has fuel and spark but will not start? If all you did is change the crank sensor then I am not sure we have fuel and spark because this is all that would effect. The PCM uses the crank to determine when to fire the plugs and injectors along with engine speed but if you have spark and fuel then we need to clarify how you confirmed this.

We need to make sure the injectors are firing and not that you just have fuel pressure. Here is a guide on how to check for injectors firing:

https://www.2carpros.com/articles/how-to-test-a-fuel-injector

Then we need to check for spark by pulling a plug and holding it against the block and crank the engine to see if it fires.

Here is a guide that will help with these things in general but let us know about this info and we can go from there:

https://youtu.be/dCjmRL3p4Cs

So clearly you got a faulty CKP sensor. This unfortunately is not uncommon so I would take it back and have them exchange it for you.

I am not sure I understand. Your not starting issue started after you replaced the sensor, you put the old one back in and it now it starts but it stalls sometimes and is sluggish? Then you put two other sensors in from two different stores and it still stalls randomly and is sluggish? Or it only stalls and is sluggish with the old sensor in it?

Your statement that you need to remove the key to get the engine to crank leads me to think it could be the security system, which disables the starter and injectors, try a passkey relearn: GM PASS LOCK RELEARN- Ignition to "run" position, try to start and let key return to "run" position
Approx ten minutes security light will go off
Turn key "off" and wait 5 seconds
Repeat 2 more times for a total of 3 relearns.
Turn key off, then start it.

There is a Tech bulliten about the ignition switch indexing be off, read it below! Diagnostic Information for Intermittent Vehicle No Crank/Dead Battery TECHNICAL SERVICE BULLETIN Reference Number(s): 04-06-03-002, Â Date of Issue: Â February 05, 2004 Related Ref Number(s): 04-06-03-002 ARTICLE BEGINNING SERVICE INFORMATION When diagnosing a concern regarding an intermittent vehicle no crank or dead battery, technicians should remove and reinstall the ignition switch using the Ignition Switch Replacement procedure in the Steering Wheel and Column section of SI. The ignition switch may have been misindexed in the steering column during a previous replacement. If the ignition switch is misindexed in one direction, the ignition switch circuits will not be completely open when the ignition switch is in the OFF position with the key removed. This may result in lights remaining on or instrument panel lights illuminating, which will drain the battery. If the ignition switch is misindexed in the opposite direction, the ignition circuits will open correctly but the ignition switch may not close the crank circuit properly when the ignition key is turned to the crank position. This will result in a no crank concern. Press Ctrl+F to find exact text Affected Model(s): 2004 Buick Rainier; 2000-2004 Cadillac Escalade; 2002-2004 Cadillac Escalade EXT; 2003-2004 Cadillac Escalade ESV; 1998-2004 Chevrolet Blazer, S-10 Pickup; 1999-2004 Chevrolet Silverado; 2000-2004 Chevrolet Suburban, Tahoe; 2002-2004 Chevrolet Avalanche, TrailBlazer, TrailBlazer EXT; 2003-2004 Chevrolet Express; 1998-2004 GMC Jimmy/Envoy, Sonoma; 1999-2004 GMC Sierra; 2000-2004 GMC Yukon, Yukon XL; 2002-2004 GMC Envoy, Envoy XL; 2003-2004 GMC Savana; 2004 GMC Envoy XUV; 1998-2004 Oldsmobile Bravada; 2003-2004 HUMMER H2 Page 1 of 1 2/19/2010 .
Check email for the proceedure.

Your cranking problem fits the description of a mis indexed switch. You might want Chevy to check it for you.

There is another tech bulliten on the driver's seat wiring harness chaffing on the seat rail, have a look there, it also can cause a no start.. Here's the TSB:
INTERMITTENT NO START, SERVICE STABILITY MESSAGE, ABS LIGHT ILLUMINATED, MULTIPLE DTCS, DIC SHOWS UNKNOWN DRIVER, VARIOUS ELECTRICAL RELATED CONDITIONS (REPAIR AND/OR REROUTE SEAT WIRING HARNESS) TECHNICAL SERVICE BULLETIN Reference Number(s): 03-08-50-014, Â Date of Issue: Â August 20, 2003 CADILLAC: 2003 Escalade, Escalade ESV, Escalade EXT CHEVROLET: 2003 Avalanche, Silverado, Suburban, Tahoe GMC: 2003 Sierra, Yukon, Yukon XL SECTION: 08 - Body and Accessories Related Ref Number(s): 03-08-50-014 ARTICLE BEGINNING CONDITION Some customers may comment on any of the following conditions: Vehicle intermittent no-start "Â Service Stability Message "Â ABS light illuminated "Â Multiple DTCs set "Â Driver Information Center (DIC) shows unknown driver "Â Various electrical related conditions "Â CAUSE A chafed or pinched seat wiring harness under the driver seat may be a cause of this condition. Because of the routing, a portion of the seat wiring harness may rest on the inboard edge of the seat track or frame. Over time, the harness may be pinched or chafed because of the seat movement. Refer to the illustration below ( Fig. 1 ). The illustration shows the inverted position of the seat bottom. The arrow shows the primary location of the possible harness chafing/pinching. CORRECTION Inspect the routing of the seat wiring harness. Reroute the seat wiring harness and attaching harness fastener (1 in Fig. 1 ) to the opposite side of the seat module bracket. Repair the harness as necessary. Refer to Wiring Repairs in the Wiring Systems sub-section of SI. The seat may have to be removed for ease of access and proper repair of the wiring harness. Fig. 1: Sear Wiring Harness If any of the above conditions still remain after this repair, refer to SI for further diagnostic information. Page 1 of 2 INTERMITTENT NO START, SERVICE STABILITY MESSAGE, ABS LIGHT ILLU...2/21/2010