2010 Aveo (US)- Intermittent Start Issues

[Phlemz]

First time post, but I've been using this forum for years to troubleshoot my way through quite a few problems. I have a manual transmission 2010 Aveo (US) that has been having some issues getting started. I was pulling a three point turn a few weeks back and it stalled out on me. After rolling it into a space, I tried restarting it a few times, the first of which it started, then died in idle, then started, turned over and died, and then was completely unresponsive. Tested the battery, fuses, starter etc., and all were getting power. Once I got it towed back home, it started right up, no problems.

So, I went with the most obvious and easiest fix and replaced the CKP sensor (that thing is a PAIN to get into its little burrow). The car ran fine for about 2 weeks, and then started dirty the past few times (noticeable half burnt fuel odor outside the vehicle), only to have the same issue return (luckily it's parked out in front); the engine turns over and starts, then dies in idle, then it starts, and turns over but dies immediately, then it is completely unresponsive (but the lights, radio etc. all turn on). If I pull the cables on the battery and drain the ECM, it will run that same sequence of starting and dying within a few hours. Otherwise, it takes about 24 hours for it to start up again. Once I get it started, I can get it around the block, but I haven't ventured further for fear of getting stuck.

This last time around I had some time to kill, so I cleaned the MA flow sensor and throttle body (battery was disconnected and it was completely removed before cleaning), which didn't change much. This leads me to think:

1. The cheap-o CKP sensor I replaced it with may have crapped out.
2. It may not have been the CKP sensor to begin with, and although I replaced it, it just so happened to run fine for a few weeks with it and some other ECM related issue is occurring.
3. Possibly an ignition issue? I have 3 different keys to this car, and switching them doesn't change anything, but maybe the immobilizer can be acting up, which might explain the dirty start (obviously this could be built up fuel from an incomplete start), and intermittency of the issue.
4. Fuel pump or fuel pump relay? When I do get a full start the pump does kick on and I do get spark and combustion for a good 5 minutes.

Again, it hasn't thrown a code this entire time, so when running diagnostics on my ODB2 everything looks fine in terms of sensors being active etc. Anyone have a hunch?

[Brit]

Hi Phlemz, my first post also. I have a Chevy Blazer as we'll as the Aveo. It has a Security function which, when the ignition key is misused, as in someone trying to jimmy it, shuts off the file pump. You mentioned issues with your Aveo pump.
Not to gloat, but there's actually nothing wrong with the Aveo at the moment.

[slayerized6]

Is the engine atleast turning over when you turn the key?

Where are you smelling the unburnt fuel? In the engine bay or at the tail pipe? Bad smell at the tail pipe can mean a clogged cat.

Your car needs air/fuel/spark to run. I would do/check a few other things.

-Change plugs, wires, and coil pack. Note if there is oil on the plugs. You can even use a spark tester to see if each cylinder is getting spark
-Check fuel pressure at the fuel rail using a gauge.
-If everything above still doesnt work, do a compression test and/or leak down test on all cylinder