Originally Posted by 9157

I am not sure if I just got lucky or am a outlier but about a month ago my ‘06 with 105k miles, started the gas fume smell after fill up and it seemed to get worse; at first the odor would go away at 3/4 tank but eventually as time me went on, it progressed to 3/8 tank before it would go away. I thought for sure I had all the symptoms of fuel pump elbow crack.
while researching, I came across a YouTube video that stated it was the gas cap as the cause.
i ordered an OEM new gas cap from eBay and installed it with 1/4 tank of gas and had no odor before the install.
I immediately filled it up the nozzle shut off and much to my surprise and delight it worked! No oder at all!!!
I even canceled my appointment with my local dealer that was to perform a smoke test on Monday!
also, the OEM gas cap has a new design from GM.
I strongly recommend trying a new gas cap as your first step in diagnosing the issue. U might be surprised!!!

Originally Posted by g_scott_smith

New cap just arrived from Amazon ... unfortunately it does not fit right. Gotta check the part numbers. But I'm going to try a new cap first thing when I get a proper fitting. I have tried to remove the cap and cover the filler with plastic (TIGHTLY) and foil in an attempt to see if the leak is at the cap. It smells like it's coming from the wheel well more and underneath. Did you try any diagnosis besides the gas cap? What kind of weather conditions were you having when it was smelling? It's been pretty cool even for this time of year here in the Tampa area.

Thanks !!!

Originally Posted by 9157

I’m in Naples so similar weather. It’s been cool almost all winter except to a couple of days.
I actually was going to return my new gas cap as the gas one delivered was a different part number and looked different. It checked with several other venders and they confirmed the one I have is the new part humans design. It fits perfectly except the tap to secure it to the door is not as snug as the original. The new cap has no play whatsoever when tightened. My only of cap would click several times but was loose and could be pushed down. The new cap does not do that.
Surprisingly, I never had a cel with the old cap.

Originally Posted by g_scott_smith

My current cap acts the same as your old one. I'm not getting any codes for the cap but for the cost need to try replacing it. Too late to get anther from Amazon. I have a diagnotic appointment Monday. I guess I'm calling around to dealers and see if I can find one tomorrow. If it's the cap it sure would save ALLOT of money. Any harmonic balancer/torque tube/clutch issues for you so far?

Originally Posted by 9157