I've been told that a number of times as well by dealerships from many different marques, and to that ignorant suggestion I always reply, "Only a fool is naive enough to dismiss the power of the internet and the knowledge base that it contains. Are you a fool?"

That response has worked every time.

 

Bought new 2008 Mazda 5 last month. On third tank of gas the gas cap stuck. Finally got it to move, but now just spins and won't open. Looking at various forums, seems to be a problem with Mazda 3's and 5's. I will drive car (on fumes) to dealer today, but am expecting a hassle. Need to know if this is a CONFIRMED and DOCUMENTED problem w/Mazda. Most importantly...is there a permanent fix? Can't live with this uncertainty.
BTW, live in Oregon, which does not have self-service gas. It was the station attendant who couldn't get it open. Husband and son also tried; no luck.

 

Just picked up one of the last new '08's on 2/18. Wife filled up last week. I went to fill-up today and couldn't get the cap off. Once I did the manly thing (you know apply force and frustration to break the item in question) I was successful in separating the black "cap" from the white "plug". The plug's lip was exposed due to the misthread so I did the logical thing and jammed the entire plug in (to reset the thread). I was then able to unscrew it by hand. If you have a problem like this, my suggestion is that you look from below and see if you are misthreaded. Had I done that before ripping the black cap off I could have rest the thread and saved myself the $31 (or potential warranty claim hassle). I cannot imagine that this is ever a vacuum issue. The white plug has a vent and would appear to breathe rather freely; i.e. no seal.

 

Took the Mazda 5 w/stuck gas cap to dealer. Expected hassle. Pleasantly surprised that they knew about problem and had a replacement cap on hand. I had them show me the difference in threading, so I could have some confidence problem won't occur again. They even gave me a copy of the Service Bulletin, which is Bulletin # 01-050/08

 

Just came back from dealer, who installed revised gas cap on my new '08 Mazda 5. Mine stuck on 3rd gas fill...only 900 miles on car. Dealer gave me a copy of the Service Bulletin covering 08 & some 09 Mazda 3's and Mazda 5's...any produced before September 12, 2008.
The Service Bulletin No is 01-050/08, dated 11/25/08. Thought this might be helpful to others, in case your dealer service dept is clueless.

I had them show me the difference between old cap and new cap, so I could better understand the issue and have some confidence that new cap will indeed be a fix. Fingers crossed. Love car otherwise, but this is a major bummer if it happens again.

 

HAHAHAHAHAHAH!!!! I LOVE it!!!
Dale, you've got *****, my friend. Nice come back.

 

Wow Mazda actually acknowledges that there is a problem..Back in Dec I had my gas cap replaced...Well guess what?? a week ago while attempting to fill up BAM stuck cap again...How I miss my Civic...Wish the Stream was released here..The 5 has been a great vehicle so far , but this issue really Sucks...I did manage to reseat the cap and get it off...But filling up should not be an issue.At my dealership they did not mention if my replacement cap was a new design or just the old design...I think I will have a nice head of steam when I take the vehicle in for an oil change...

 

Went to the dealer this am and didn't even need to reference TSB #01-050/08 (thanks for the heads up Bilyeu5!). Was in and out in about 10 minutes. Actually forgot to check out the new cap to see if there were any identifiable differences from the one that jammed. Will post if I notice anything that will identify the problem.

UPDATE-So, I eyeballed the replacement and there is a noticeable difference. On the white portion that seats in the tank's opening there is a raised (and closed) rectangle. On the prior cap, that rectangle was not closed, i.e. it was "3-sided." That is likely what causes the problem. When inserted and tightened, the cap could improperly seat on the lower of the two tiers created by this opening. If the one on the opposite side was correctly aligned, this would cause the cap to misthread and jam.

Moral of the story, if you have a "3-sided" cap, get it replaced.

 

Thanks for the info, I'll check the cap on my 2009 and report back on which type it is.

FWIW, I have a "3-sided" cat, should I get her replaced as well.

 

I checked my gas cap and I have what beardgod described as "a raised (and closed) rectangle" on either side of my cap versus the "3-sided" version of the truth. So, for the 2009 model year of the Mazda3 at least, the new cap design came from the factory.