THE GREAT MAZDA SCREW UP
If your Mazda 3 generates a check engine code that says something to the effect of "Large EVAP leak detected" then this will probably apply to you. If your Mazda 3 starts leaking tons of gasoline when you fill up the tank, this definitely applies to you.
The fuel tank lock ring, or the plastic ring the has threads on it to secure the fuel pump has probably failed in a major way. The plastic ring literally splits down the middle and suddenly there is a huge hole in the top of the gas tank. The evap code will point to this but it would be very hard to detect without pulling the fuel tank out, so most people ignore it. Eventually the plastic ring splits wide enough to let gasoline spill out and you are forced to deal with it.
There is no way to remove and replace this ring without pulling the fuel tank out. Although there is a small access port underneath the back seat, it is used for disconnecting the wiring to the fuel pump, not replacing the ring. There is simply no space to put a tool in there and the ring is on hella tight.
Aside from disconnecting a few annoying evap hoses, the fuel tank is relatively easy to remove as long a you can get your fingers in the tight spaces to use a fuel disconnect tool to unhook the fuel and evap lines. The ones on the rear near the evap canister are the worst and be prepared to use a lot of zen concentration and beer. The real challenge is getting the old ring off without destroying the fuel pump. Its all plastic so for craps sake go easy. The torque on the ring is between 59-89 ft. lbs for some reason but I would be careful not to tighten it too tight. You might need a tool like this one by Lisle . It worked pretty good for me but then I was always lucky. Good luck and send Mazda a flaming bag of poop for using such a crappy design.
P.S. the new plastic ring from Mazda dealer is $75. More flaming dog poop required for that debacle too.
