"Check Gas Cap"

[guitarfish]

Hey guys, I'm suddenly getting some "Check Gas Cap" messages on my '08 Prix's console. I read that the Evap Vent Valve is a common failure item that causes this.

I understand this somewhere near the fuel filler neck. Can anyone tell me how to get to it, and what's involved in replacing it?

Thanks,
-Dave

[BNaylor]

Best to get it scanned and see what the specific evaporative emissions code(s) is. First item to check is the gap cap. Make sure it is tight and and the seal is good. Since this is an '08 model you could take it to the GM dealership since the emissions fault should be covered.

[guitarfish]

Thanks for the reply. I don't know why I always forget that emissions are covered up to 100K. I'm at 62K right now. In any case, the gas cap error appeared 3x throughout the same tank of gas. Since then I've gone through two full tanks without seeing it. Any chance it could be a bad fuel issue? I don't understand the workings of the sensors that would detect a loose gas cap. Is it related to pressure or something?

[tblake]

Exaclty right, the evap system actually uses slight engine vacuum to pull vacuum on the fuel tank. This vacuum is measured by sort of a MAP senson on top of the fuel pump pod.

Could it have possibly just been a loose gascap? If you got the code 3 times in one tank, then filled up, and havn't seen it since... Maybe this tank of gas you got the cap tight. I dont know. I think I would drive it and see if it comes back on.

BTW, how is your car doing lately? Figure out what that suspension clunk was?

[guitarfish]

I guess I'll just see if the gas cap message comes back again. Taking it to the dealer is a lot hard there days - two of the closest GM dealers are now gone. It's 30mi to the closest one now.

The car itself...still hearing some residual noises & things that I'm 100% sure are related to the subframe issue. The klunk noise was a motor mount, which was under the derpentine belt area. They replaced it, the noise went away for almost a month now, but there's still some other wierd noises.

I'm not a car expert but 25 years of fixing everything from appliances, computers, cars and everything else imaginable has given me a lot of insights on how stuff works. And I know that when you drop a 1,000lb engine/tranny 8" all that energy has to get absorbed somewhere. All kinds of pressure was put on components on that car that aren't designed to handle that stress, so it's no surprise to me that I'm still discovering wierd problems. Finding the source is another issue, though.

But thanks for asking!!

[tblake]

Sorry to hear that. BTW, the only person that hears all those little clunks is you. If you dont point them out, I'll bet no one else will hear them. It just sort of is frustrating. Did you have a look at your upper dog bone motor mounts at all?