So we all hate to casually be driving down the road then BAM Check Engine shows up out of nowhere. Well I'm not sure if that happens to everyone but it happened to me. The situation is I got my car a 03 Trailblazer it was doing just fine then the check engine light came on so I took it back to the deal and he said he would get it checked out. When it was fixed I picked it up and asked him what was wrong and he mumbled on about something that I couldnt hear about the fuel system. So since he was in a hurry to go back inside to his family I just left. The car did fine for a few months the only thing I noticed was when I got gas it would click off as if the tank were full and I would have to hold the lever manually. Then I thought maybe it's the rubber surrounding the gas tank so i took that off and it would pump just fine. Then after a month or so it started doing it again so I would just barely put the nozzle in the tank and it pumps just fine. So that's one thing I've always thought was weird. That's not what the check engine light is about though. Just thought I would ramble on about where it all started. So I got an error code reading on it and it came back as: "Determined to be a small leak existing in the evaporative emission control system". So I'm thinking that it's the thermostat. There have been times where it would come on then go off for a while then just come back on out of nowhere( talking about weeks not hours or days). Now it came on and hasnt gone off. I'm just wondering if it could be something simple like the thermostat that I could change myself. Or if I should take it to the dealer to get fixed. I've been putting it off since for some reason I don't trust them at all and all the work I've ever had done to a car I've done myself. It is still under warranty but I just don't want them haggling me and it being something simple like that and them come back and tell me my transmission is blow lol. Yeah, I'm paranoid but can't be too cautious.

Vandy-1

The easiest thing you can do is check all the vacuum lines and hoses that run between the fuel tank and the vapor cannister and to the motor for any cracking or leaks. If any are found replace them and have the cel light reset and code cleared. A worn out gas cap that's not sealing could also be your problem.

igottogonow

You may want to invest in a code reader. I did it (ebay), it paid for itself the first time. If under warranty I'd still use it don't worry about what they say. If they make it an issue notify Chev or better business buearu. My wife works for dearler and they dearly try to avoid these type complaints. Like Vandy-1 said check vapor cannister, lines and fuel cap. I had same problem with 02 Jeep, code reader showed it to be one of these. I replaced gas cap because it was cheaper and easier but it turned out to be the vapor cannister. Not sure what a thermostat has to do with it.

jennapbt

Yeah I thought about checking the lines. It's the same error that keeps popping up its just a matter of ruling out what it is of course. I wish it were as simple as the gas cap but I just bought a new one w/ a lock. Maybe I'll just take it in when I get a chance. Hopefully they don't screw me in costs

Vandy-1

As igottogonow pointed out a code reader will pay for itself in 1-3 repair costs.
True the thermostat would not be your problem likely a leak in a line somewhere.
Could also be your purge valve is malfunctioning intermittently. Your cheapest bet is
to check all your lines first as vapor cannisters are kind of expensive $ 120-200+ on
average. Any rubber lines that are in quetionable condition i.e. dry rot, cracked, hardened,
swollen should be replaced.

jennapbt

Well the mystery is figured out but not yet fixed.

Here is the story: I took it to a Chevy dealer to get everything fixed yesterday. They took it to the back and did a full diagnostic on it. When they came back to tell me what was going on they said they pulled up 3 error codes. 1) Thermostat reading below normal. 2) EVAP system malfunction. & 3) EVAP small leak in system. That was the "good" news (or so called good news). The "bad" news was that my warranty company had red flagged that particular establishment and I could not get any repairs done there that they would cover it would have to come out of my pocket. The only thing they actually covered was a new Fuel Tank regardless. By the time I found that out it was 5 o clock and too late to take it somewhere else and I have to work all weekend. He did say I can take it to ANYONE else just not them... pretty strange.

So I was sitting here thinking about the error codes and reading up on them and just couldnt figure out what could be the main source of all of this. So I said forget it and went and crawled under the car. I started with the lines/hoses. Well the first thing I saw was on the back on the tank on the bottom I noticed a corrosive type thing going on and automatically thought crap a gas leak which is pretty obvious. I could smell gas like crazy also. I kept following the hose I was on and it lead me to where the hose and the tank meet. That's where the source of the leak seems to be coming from also. I felt around the hose and didn't feel any immediate cracks or anything like that. I'm assuming there is something going on with the tank AND the hose, since it looked like it wasn't leaking directly from a small spot from the hose, looks like its around the tank also. On the tank where the hose meets it there is a black plastic type sealant on it which was chipping off. Then I started to remember about what I mentioned about me taking it to the dealer about a fuel problem. So I figure they put that on there as a "quick fix" and didn't really fix the problem only delayed it. So that explains error # 2 & #3. They fit together with my bad gas mileage, gas smell lingering in the car, pumping gas malfunctions, and running sluggishly.

As for the t-stat. I'm going to change the sensor first and clear the code and see if it comes back if it does I'll then change the t-stat and flush the coolant at the same time of course. The t-stat isn't my biggest concern right now since it's under heating rather than over heating. The EVAP system needs to be addressed right now. For sake of my dropping gas into it every 3 days and taking a risk of causing more damage.

So I'll be making an appt. to take it into another Chevy dealer to get a new fuel tank. Hopefully that will fix everything, well I'm pretty sure it will. It's just the little details I worry about like will there be a new fuel pump and sensors with the new fuel tank or will they use my old ones. So I guess I'll just have to ask them when that time comes.

Wish me luck everyone and hope I don't get screwed by the dealer lol, j/k. Can't wait to get the Trailblazer action back to tip top shape, and of course the better gas mileage I'm REALLY looking forward to.

I'll repost after it's fixed to let everyone know what went on. Thanks everyone for their advice.

Vandy-1

I would encourage you to also change the t-stat IF you're "overcooling" that's as bad in a way as overheating as the car cannot run as efficiently if not at full operating temp. Sub systems can also be affected such as the fuel system running richer hence worse gas mileage. Unless you specify a new pump I would think they will use your old pump with the new gas tank. Good luck with it !