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I have a 2002 Trailblazer giving me a fit. The problem only occurs after it has reached normal operating temperature and the truck is turned off. It has a new fuel pump, fuel filter, and the harness was inspected at install which was 7,000mi ago, but I would not think that would have failed since then. As soon as the truck is shut off it will not start until you let it sit for 20mins or so. Then it fires back up and runs fine. NO CODES!!!

Also, I did have a bad coil 2,000 miles ago. Replaced all spark plugs, and the bad coil. But that issue seems to have been resolved as well.

Any help is appreciated.

When it does nto start does it have spark or fuel pressure?

I've run into a few of the vvt valves screwing up.

Ive had a few crank and cam sensors act up when hot. I think the cam sensor provides the spark/noid syncronization. I certainly would want to know whats gone when no start, noid, spark, fuel pressure? Was it a Delphi pump? Why was the harness changed 7,000 ago?

Well all, sorry for the delay in response but I may have figured this mess out. apparently the vehicle would run fine and intermittently not start when hot. I performed all the necessary tests - fuel - cam - crank - injectors - etc... Found all to check fine. All in spec. Then, it lost signal to the Engine Coolant Temp Sensor, the temp gauge dropped to "0deg" and the truck went to full rich. I turned it off and it would not restart. Let it sit for 10 mins and it started - but hesitated. It was "flooded". I need to test the ECT and harness, but I am pretty sure it may be a bad sensor at this point.

I'll let you know as soon as I get back to it.

Make sure of the ground. I know on earlier ones there was a harness update where the ground lead was attached to the block eliminating the ground in the harness.