check gas cap light

[jddem]

2001 ssei 64000 miles. no other symptoms i can think of.

i filled my tank with 92 octane. added lucas 5oz bottle (this is all normal)
short time later check gas cap light came on.

put new,cap in and reset light. . approx 1/4 tank later light came back on.

Previous owner said they had this problem before when "overfilling" tank and dealership said that it was common and in time it will go out. (previous owner is my father, he bought car new)

any idea , should i let it go or has someone else had this problem?:

thanks

[1tinindian]

I'd say you are having an EVAP small leak problem.
Even though the gas cap is being identified as the cause, other small leaks in the evap system can also set the same message.
Without using smoke to find the leak, you'd be only guessing at this point.

[1tinindian]

double post

[Abbby]

wrestled with this on both of my bonnevilles. Changed gas caps and kept cleaning the filler opening and resetting the code. Did not fix. There is an evap device under the hood right on top of the front valve cover. Not sure what it is called. Changed that on both vehicles and gas cap code gone forever.

[jddem]

pic?

[Abbby]

ACDelco 214-641 GM Original Equipment Vapor Canister Purge Valve. $24 on Amazon.com

[CMNTMXR57]

As Leon mentioned, it's more than just gap and seal against the filler neck as well as potential EVAP Canister. You have to diagnose the purge solenoid (if it's functioning when commanded to), as well as all hoses/plumbing which involves a smoke machine to see if there is a leak. What happens is that there is a decay rate in the system that is quicker than anticipated by the PCM.

[bonneville_gal]

I had gas cap issue on my new car. Had started with previous owner, they bought a new aftermarket gas cap that didn't solve it. When I bought it I swapped off the gas cap from my SLE onto the new SSEi so I know it's the right gas cap, not aftermarket issue.. still had warning.

My mechanic (a 'can fix anything' backyard kinda guy sometimes) said to make sure there wasn't any rust at all on the filler tube as that could cause problems in air pressure seepage, so sand it down to remove rust and slather with vaseline. I was skeptical... but I tried his fix.

Rinsed everything out in the gas cap area with a hose. Stuffed filler tube first with a damp rag to make sure no gas fumes coming out when I sanded metal (be careful!). Used a fine sandpaper sheet folded to be flexible and hand sanded outside, just inside and exterior of filler tube to remove the rust on the surface (there was definitely some), and then slathered it with Vaseline to provide a good wet seal. Cranked down gas cap and marvel of marvels.. it worked! Annoying gas cap warning light now gone!! Has lasted for a month so far so good..

So that's a place to start...

[CMNTMXR57]

Yes, I've recommended that process to several on here before as a cheap starting point.