Thanks, I will see if I can blow air through the line and also check the line from the engine to the canister in the back.

I may able to take out the charcoal canister and see if it's full of dirt or fuel. Hopefully I won't have to drop the tank.
I wonder if this will help clear the P0300 code which I noticed is causing missfires on all cylinders nearly equally. Once warm, there is 0 missfires... One issue at a time.

The P0573 is the third (top) brake light? Will add that to the list of checks.

In responds to the O2 sensors and spark plug brand, I will have to look at I did not install them.
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P0300 does NOT mean "random misfires" it means "unidentified misfire".
If the tube to the purge valve was holed there would be a lean, unmetered air. If the purge valve is open there is usually a "hard start" due to too much air, anti-choke.
The P0446 test commands the opening of both valves then measures the pressure in the tank. Opening the Purge valve would do the same thing as a hole in the EVAP line. QED the problem is between the tank and the exit side of the valve.

Furthermore, the purge valve is normally closed and the vent is normally open. Meaning that key off the purge is closed and the vent is open.

 

BTW, triggering the vent valve can be done easily by applying voltage to the wires. A 9 volt battery would do it.

 

Thanks for all the great info Don, I will use that and do more investigating asap! Much appreciated!
side note: wiring diagrams would be handy to have.

 

Not sure what the makes the sensors are that the mechanic installed. He mentioned he used OEM but who knows... Also the ethonol was at near 50 percent and I reset it back to zero when these problems all started. It stayed at zero for a while and is now at 11%.

 

If you are a bit of a windows hacker send me a PM.

 

But you didn’t answer. Has the car ever tasted E85?

The P0300 was surely caused by the outawack ethanol%, which caused the P0172. Been through that myself, posted here on a couple threads.

My 2011 2.2 with P0172 and smokey sputtering starting problems, had 50% stored, even though sample tested 11%, Reset to 0%, immediate fix, it eventually (couple of weeks) went to 10% stored, consistent with the E10 they sell here.

These GM FlexFuel cars, not just HHR (even found a case with later model pickup truck,) occasionally get confused and think there’s a bunch of ethanol in the tank when there isn’t. Runs horribly rich sputtering and smoking, or won’t start at all initially. Once it starts, which may take a flood-clearing pedal-to-the floor, it will settle down once it gets warm enough to go to closed loop and run great, but then sets the P0172 because it’s worried about the large leaning trim needed to get to correct the rich condition. There’s a TSB on it, and resetting the ethanol % is indeed the known fix.

I had (and after much time and several attempts to fix, still have) a P0442 (evap small leak) which I think may have contributed to the computer confusion. Now, since you have the P0446, I wonder if evap problems generally can somehow trigger this ethanol % confusion.

So it seems your mechanic, with all that work, did absolutely nothing to fix your actual problems.

i’m chalking this up to ANOTHER P0172 ethanol problem. Bottom line, when a GM FlexFuel car throws a P0172, read the stored ethanol % and compare it with a sample from the fuel tank. Do this first.

 

Hey sorry, no I have not tested for ethonol percentage. I happened to see a video on this and testing not long ago. That is why I reset the ethonol back to zero.
I will add that to the list to check. How would I avoid ethonol as our gas all contains at least a bit of ethonol in Canada.

On another note:
I had some time today and talked to a friend of mine whom works at Chevy. He sent my info to the mechanic.

I said I might be getting a blockage between the charcoal canister and the fuel tank / fuel pump as per what donbrew mentioned.
The mechanic responded with "Yes. We would normally replace the e charcoal canister with that repair and if the code (P0446) returns, r/r tank for a restriction at tank side."

He said first unhook the canister and see if it is heavy. It should be fairly light. Plastic and charcoal doesn't have much weight at all. Also tip it and see if any fuel comes out or other contaminants.
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I've heard that if you top off your cars fuel, it can run back into the canister and over saturate the canister cashing damage.

As far as pinched lines go, I do recall the guy saying he fought getting the tank back in there after replacing the pump. Great....

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I will report back when I get some time to get under the car.

 

Pulp isn't asking if you tested for ethanol content. He's asking if E85 has ever been put in. I had to read it twice, the brain reads tasted, in this car repair forum, and thinks tested.

But you did say that you've reset it, and now it's registering the correct ethanol content.

 

Ya that can't taste good haha.
I just use what ever the regular grade fuel is at the station. I will look next time I'm there.