Getting message?:"Tighten Gas Cap" or are you Unable to fill your tank? ! Look here !

This is the part I bought, which all the parts websites said is the correct part for my 2004 Tahoe LS.






But this two-piece kit is also available, althought the websites say this is NOT the right kit for my Tahoe.






Here is what I see when I crawl under my truck.

This is near the back of the gas tank. This rectangular piece looks a lot like the one in the two-piece kit above.





This is the Evap Canister mounted on the side of the gas tank.




One of the lines from the Evap Canister leads to the unit pointed to by the arrows in the next three photos. I can't tell if this is the other part shown in the two-piece kit above. Does anyone know what this part is?










Finally, this is a little more forward. I'm not sure what the arrow is pointing at, but I don't think it's part of the evap system. Maybe part of the 4WD shifting system? I have no idea.





Here are a couple of GM diagrams I found, and a couple of pages from the GM manual. I see there is some confusion between "purge valve" and "vent valve". The manual says the purge valve is under the hood, on the intake manifold. But I have looked at that, and the part I bought is much bigger. I think other GM trucks, especially pickups, have the part I bought near the gas tank. And I think what I bought is a "vent valve" regardless of the word "purge" in the name of the part.















Any ideas on what I have here?

THANKS.

OK, the cylindrical part is a redesigned replacement for the box shaped part at the back of the gas tank. Got it replaced and am waiting for the EVAP check to complete (reset the codes). Now I'm fighting the dreaded P0101 MAF DTC problem. Think I'll buy another GM..... um, no....

scrnchr said:

OK, the cylindrical part is a redesigned replacement for the box shaped part at the back of the gas tank. Got it replaced and am waiting for the EVAP check to complete (reset the codes). Now I'm fighting the dreaded P0101 MAF DTC problem. Think I'll buy another GM..... um, no....

Click to expand...

So which picture is the one that shows the Solenoid?

scrnchr said:

OK, the cylindrical part is a redesigned replacement for the box shaped part at the back of the gas tank. Got it replaced and am waiting for the EVAP check to complete (reset the codes). Now I'm fighting the dreaded P0101 MAF DTC problem. Think I'll buy another GM..... um, no....

Click to expand...

Umm.... They all have their problems. Nobody makes a perfect vehicle. They all aim for satisficing.

No, I didn't misspell satisfying. Satisficing is a real word.

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So I just finished installing the part; I haven't been to the gas station yet but I will soon. I took a pic showing the placement of the part on the truck:

You can see it with the wire loom and the hose coming from it, in front of the axle attached to the underbody with a clip which is somewhat difficult to remove. The hose clip is a little tricky but came off easier than the clip for solenoid. Scale of 1-10 1 being easy 10 being hard I'd say it was a 3. Mostly because of the awkward positioning for me to try and get the clips off. Would've been easier on a lift. Only necessary tool was a flathead screwdriver.

Damn all of you. I read this thread, and even posted 2 weeks ago. Now I'm suffering the same problems. Got the fuel cap warning message earlier and the P0449 today. Looks like I'm fixing the truck on Thursday.

Edit:~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

There is a TSB on this as of April 2011 for NNBS trucks. Bulletin number is 09-06-04-028C. There is a revised evaporative emmissions (EVAP) canister vent solenoid (CVS) valve assembly. The revised EVAP CVS valve vent pipe attaches to the fuel tank filler neck. New p/ns are 20995472 for the EVAP CVS valve assembly and 19257603 for the jumper harness. Expect to spend ~$80. Service department can provide you with detailed install instructions should you want to attempt this. Looks very simple and will attempt to do this myself tomorrow afternoon. Book time for the dealership is .8 hours. I hope this helps.


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I'm still having trouble with this. The first day I filled up after the install (about two weeks ago), it clicked twice initially trying to pump gas, but then let me fill the whole tank. So I thought the problem was solved. Today I go to fill up again, and it's back to square one. Clicking every f#%^ing 5 seconds! This is annoying as hell...
Any more ideas on fixing this? Did I just waste $25???

Eschrichtius said:

I'm still having trouble with this. The first day I filled up after the install (about two weeks ago), it clicked twice initially trying to pump gas, but then let me fill the whole tank. So I thought the problem was solved. Today I go to fill up again, and it's back to square one. Clicking every f#%^ing 5 seconds! This is annoying as hell...
Any more ideas on fixing this? Did I just waste $25???

Click to expand...

Read my post above yours. It tells you everything.

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domin8 said:

Read my post above yours. It tells you everything.

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Click to expand...

What is a TSB? So this new part is going to resolve the issue now? Have you tried it yet?

I don't know if that new kit will solve your problem or not, Esch. My issue was the code being thrown and not passing emissions. I never had the clicking off while filling problem.

Anyway, I bought a MAF sensor at a junkyard for 40 bucks, popped it in and the P0101 code went away. Then the truck got stuck in 4WD. I ended up replacing the transfer case encoder motor. Royal pain in the butt. I cannot allow myself to buy any more GM trucks...